Here are lists of single-sex education (schools which only admit boys, or those which only admit boys at certain levels/years/grades), or those which follow the Diamond Schools model (separating students by gender at points), by country.
Australia
Austria Former Theresianum (now coeducational)
Argentina Colegio del Salvador, Buenos Aires
Azerbaijan Agdash Private Turkish High School, Agdash Former Baku Dede Gorgud Private Turkish High School (closed) Baku Private Turkish High School (closed) Sharur Turkish High School (closed)
Bangladesh Barisal Division Barishal Zilla School, Barishal Barguna Zilla School, Barguna
Chittagong Division Annada Government High School, Brahmanbaria Bandarban Zilla School, Bandarban Chittagong Collegiate School, Chittagong Comilla Zilla School, Cumilla Cumilla Cadet College, Cumilla Hazi Mohammad Mohsin Government High School, Chittagong Nasirabad Government High School, Chittagong Noakhali Zilla School, Noakhali
Dhaka Division Faridpur Zilla School, Faridpur St. Joseph Higher Secondary School, Dhaka Sher-e-Bangla Nagar Government Boys' High School, Dhaka Siddheswari Boys' High School, Dhaka
Khulna Division Jashore Zilla School, Jashore Khulna Zilla School, Khulna Kushtia Zilla School, Kushtia Manirampur Government High School, Manirampur Victoria Jubilee Government High School, Chuadanga
Mymensingh Division Jamalpur Zilla School, Jamalpur Mymensingh Zilla School, Mymensingh Sherpur Government Victoria Academy, Sherpur
Rajshahi Division Bogra Zilla School, Bogura Natore Government Boys High School, Natore Pabna Zilla School, Pabna Naogaon Zilla School, Naogaon
Rangpur Division Dinajpur Zilla School, Dinajpur Gaibandha Government Boys' High School, Gaibandha Rangpur Zilla School, Rangpur
Brazil Colégio de São Bento, Rio de Janeiro
Former St. Ignatius College St. Louis College
Brunei Ma'had Islam Brunei, Tutong Muda Hashim Secondary School, Bukit Bendera Rimba Arabic Secondary School, Rimba Sultan Omar Ali Saifuddien College, Bandar Seri Begawan
Note: Hassanal Bolkiah Boys' Arabic Secondary School, despite its name, admits both male and female students.
Cameroon Sacred Heart College, Bamenda St. Joseph's College, Buea
Canada
British Columbia Vancouver St. George's School Vancouver College
Manitoba St. Paul's High School, Winnipeg
Ontario Canada Prep Academy, St Catharines St. Andrew's College, Aurora Toronto Brebeuf College School Chaminade College School Crescent School Neil McNeil High School Royal St. George's College St. Basil-the-Great College School St. Michael's Choir School St. Michael's College School Upper Canada College Former De La Salle College, Toronto (now coeducational) Michael Power High School, Toronto, merged into Michael Power/St. Joseph High School Robert Land Academy, West Lincoln (1978–2025)
Quebec Selwyn House School, Westmount Former Collège Jean-de-Brébeuf, Montreal (now coeducational)
Chile Colegio del Verbo Divino, Las Condes Instituto Regional Federico Errázuriz, Santa Cruz Instituto Nacional General José Miguel Carrera, Santiago
Cyprus Former American Academy of Larnaca (now coeducational)
Egypt Collège de la Sainte Famille, Cairo Collége Saint Marc, Alexandria Kafr El-Zayat Secondary School For Boys, Kafr Az-Zayyat
Ethiopia St Joseph's School, Addis Ababa
Fiji Marist Brothers High School, Suva Former Toorak Boys' School
France Chavagnes International College, Chavagnes-en-Paillers
Ghana Ashanti Region Kumasi High School, Kumasi Opoku Ware School, Santasi Osei Tutu Senior High School, Akropong Prempeh College, Kumasi
Central Region Adisadel College, Cape Coast Mfantsipim School, Cape Coast St. Augustine's College, Cape Coast
Eastern Region Pope John Senior High School and Minor Seminary, Effiduase St. Peter's Boys Senior High School, Nkwatia Kwahu
Greater Accra Region Accra Academy, Kaneshie Presbyterian Boys' Senior High School, Legon St. Thomas Aquinas Senior High School, Osu Salem School, Osu
Oti Region St. Mary's Seminary/Senior High School, Lolobi
Upper West Region Nandom Senior High School, Nandom St. Francis Xavier Minor Seminary, Wa
Volta Region Bishop Herman College, Kpando St. Paul's Senior High School, Hatsukope-Denu
Western Region Ghana Secondary Technical School, Takoradi St. John's School, Sekondi
Gibraltar
Bayside Comprehensive School
Greece Fifth Boys Gymnasium of Thessaloniki (closed) A non-profit public secondary school in the city of Thessaloniki's Analipsi neighborhood, comprised 3-year junior high school and 3-year high school (six-grade), and also Higher Education entrance education. Previous was the Villa Mehmet Kapandji, today is The Cultural Centre of Education Foundation of National Bank of Greece.
Guam
Father Dueñas Memorial School
Guernsey
Elizabeth College, Guernsey
Haiti Collège Notre-Dame du Perpétuel Secours, Cap-Haïtien
Hong Kong
Hungary Benedictine High School of Pannonhalma, Pannonhalma Pelbart Temesvari Franciscan High School, Esztergom Piarist High School of Budapest, Budapest
India Please see, :Category:Boys' schools in India.
Indonesia Canisius College, Menteng
Iran Since the Iranian Revolution government schools have been divided by gender Tehran International School has separate campuses for boys.
Iraq Baghdad College, Baghdad
Al Mutamayizeen Secondary has boys' schools.
Jamaica Alpha Boys School, Kingston Cornwall College, Montego Bay Jamaica College, Kingston Munro College, St Elizabeth St. George's College, Kingston
Former Collegiate School
Japan
Jersey
De La Salle College, Jersey Victoria College, Jersey
Kenya Alliance High School (Kenya), Kikuyu Agoro Sare High School, Oyugis Friends School Kamusinga, Kimilili Highway Secondary School, South B Kapsabet High School, Kapsabet Kericho High School, Kericho Kiambu High School Kisii School, Kisii Kitui School, Kitui Machakos School, Machakos Maliera Boys Secondary School, Kodiaga Maranda High School, Bondo Mumbuni High School, Machakos Murang'a High School, Murang'a Nakuru Boys High School, Nakuru Nyang'ori High School, Kisumu Nyeri High School, Nyeri St. Joseph's Rapogi Secondary School, Sare St. Luke's Boys' High School, Kimilili St. Mary's School, Nairobi St. Mary's School, Yala Township St. Patrick's High School, Iten Sawagongo High School, Gem Constituency Starehe Boys' Centre and School, Nairobi
Former Baraka School Mosocho Academy
Lebanon Became coeducational American Boys College (now International College, Beirut)
Luxembourg Former Lycée de Garçons de Luxembourg Lycée de Garçons Esch-sur-Alzette
Malaysia Alam Shah Science Secondary School, Bandar Tun Razak Batu Pahat High School, Batu Pahat Bukit Bintang Boys' Secondary School, Petaling Jaya Chung Ling High School, Air Itam English College Johore Bahru, Johor Bahru Henry Gurney School, Keningau Henry Gurney School Puncak Borneo, Kuching Kolej Sultan Abdul Hamid, Alor Setar Malay College Kuala Kangsar, Kuala Kangsar Royal Military College, Sungai Besi Sacred Heart National Secondary School, Sibu Sultan Alam Shah School, Putrajaya
George Town Methodist Boys' School Penang Free School
Ipoh Sekolah Menengah Kebangsaan Anderson Sekolah Tuanku Abdul Rahman
Klang Anglo Chinese School La Salle School
Kuala Lumpur Maxwell School Methodist Boys' School St. John's Institution Tinggi Setapak National Secondary School Victoria Institution
Malacca City Catholic High School Malacca High School St. Francis' Institution
Seremban St. Paul's Institution Sekolah Dato' Abdul Razak SMS Tuanku Munawir
Taiping King Edward VII School St. George's Institution
Former St. Michael's Institution
Malta St. Edward's College, Cottonera St. Michael School, Santa Venera
Mauritius Adolphe de Plevitz SSS, Grand-Baie Cosmopolitan College (Boys), Plaines Des Papayes Dr. Regis Chaperon State Secondary School, Quatre Bornes Dr James Burty David SSS, Port Louis Ebène State Secondary School (Boys) Eden College, Quatre Bornes Patten College, Quatre Bornes Piton State College, Piton Windsor College Boys, Rose Belle
Former Royal College Curepipe Royal College Port Louis Sir Abdool Raman Osman State College
Mexico Bachillerato Anáhuac Campus Monterrey
Irish Institute in the State of Mexico has a separate campus for boys.
Universidad Panamericana Preparatoria in Mexico City has a separate campus for boys.
Namibia Former boys schools St. Paul's College, Namibia, (now coeducational)
Nepal Former boys schools St. Xavier's School, Godavari (became coeducational in 1996)
New Zealand Auckland Region Auckland Grammar School, Epsom, Auckland De La Salle College, Māngere East, Auckland Dilworth School, Epsom, Auckland Kelston Boys' High School, Kelston, Auckland King's College, Ōtāhuhu, Auckland (Junior only) King's School, Remuera, Auckland Liston College, Henderson, Auckland Rosmini College, Takapuna, Auckland Sacred Heart College, Glendowie, Auckland Saint Kentigern College, Pakuranga, Auckland - has gender separation in some classes St Paul's College, Ponsonby, Auckland St Peter's College, Grafton, Auckland Tipene St Stephens School, Bombay Hills, Auckland (opening 2025) Westlake Boys High School, Forrest Hill, Auckland
Bay of Plenty Region Rotorua Boys' High School, Rotorua Tauranga Boys' College, Tauranga
Canterbury Region Christchurch Boys' High School, Riccarton, Christchurch Christ's College, Christchurch Medbury School, Fendalton, Christchurch St Bede's College, Papanui, Christchurch St Thomas of Canterbury College, Sockburn, Christchurch Shirley Boys' High School, Christchurch Timaru Boys' High School, Timaru
Gisborne District Gisborne Boys' High School, Gisborne
Hawke's Bay Region Hastings Boys' High School, Hastings Lindisfarne College, Hastings Napier Boys' High School, Napier St John's College, Hastings Te Aute College, Pukehou Te Aratika Academy, Hastings
Manawatū-Whanganui Hato Paora College, Cheltenham, Feilding Palmerston North Boys' High School, Palmerston North
Marlborough Region Marlborough Boys' College, Blenheim
Nelson City Nelson College, Nelson
Northland Region Whangārei Boys' High School, Whangārei
Otago Region John McGlashan College, Maori Hill, Dunedin King's High School, St Kilda, Dunedin Otago Boys' High School, Dunedin Waitaki Boys' High School, Oamaru
Southland Region Southland Boys' High School, Invercargill
Taranaki Region Francis Douglas Memorial College, Westown, New Plymouth New Plymouth Boys' High School, New Plymouth
Waikato region Hamilton Boys' High School, Hamilton St John's College, Hamilton St Paul's Collegiate School, Hamilton (Junior only)
Wellington Region Hutt International Boys' School, Trentham, Upper Hutt Rathkeale College, Masterton Rongotai College, Rongotai, Wellington St Bernard's College, Lower Hutt St Patrick's College, Silverstream, Upper Hutt St Patrick's College, Kilbirnie, Wellington Wellesley College, Days Bay, Lower Hutt Wellington College, Mount Victoria, Wellington
Former boys' schools Hereworth School, Havelock North, Hawke's Bay Waihi School, Winchester, Canterbury Scots College, Strathmore Park, Wellington St Andrew's College, Christchurch
Nigeria Abia State Government College Umuahia, Umuahia Marist Brothers' Juniorate, Uturu Ngwa High School, Aba Akwa Ibom State Holy Family College, Abak Methodist Boys' High School, Oron Anambra State Bishop Crowther Seminary, Awka Christ the King College, Onitsha Benue State St. Andrew's Secondary School, Adikpo Delta State Government College Ughelli, Ughelli Ebonyi State Government Secondary School, Afikpo Imo State Government Secondary School, Owerri Lagos State Eko Boys' High School, Lagos King's College, Lagos Methodist Boys' High School, Victoria Island St Gregory's College, Ikoyi Ogun State