The women's 4 × 100 metre medley relay competition at the 2018 Pan Pacific Swimming Championships took place on August 12 at the Tokyo Tatsumi International Swimming Center. The defending champion was Australia.
Records Prior to this competition, the existing world and Pan Pacific records were as follows: World recordKathleen Baker (58.54)Lilly King (1:04.48)Kelsi Worrell (56.30)Simone Manuel (52.23)3:51.55Budapest, Hungary30 July 2017Pan Pacific Championships recordNatalie Coughlin (59.85)Rebecca Soni (1:05.35)Dana Vollmer (56.91)Jessica Hardy (53.12)3:55.23Irvine, United States21 August 2010
Results All times are in minutes and seconds.
KEY:CRChampionships recordNRNational recordPBPersonal bestSBSeasonal best
Final The final was held on 12 August from 18:00. Rank Lane Nation Swimmers Time Notes 5 Emily Seebohm (59.28)Jessica Hansen (1:05.82)Emma McKeon (56.45)Cate Campbell (51.19)3:52.74CR 4 Kathleen Baker (59.41)Lilly King (1:04.86)Kelsi Dahlia (56.72)Simone Manuel (52.22)3:53.21 3 Natsumi Sakai (59.20)Reona Aoki (1:06.84)Rikako Ikee (55.48)Tomomi Aoki (53.51)3:55.03NR 4 6 Kylie Masse (58.63)Kelsey Wog (1:07.28)Rebecca Smith (57.51)Taylor Ruck (51.72)3:55.14 5 2 Chloe Isleta (1:04.22)Miranda Renner (1:14.90)Rosalee Santa Ana (1:06.42)Nicole Oliva (56.64)4:22.18
References