CR3 or CR-3 may refer to:
Science and technology Macrophage-1 antigen, an immunological cell surface receptor for a complement component CR3, an x86 microprocessor control register CR3, a raw image format used by Canon digital cameras since 2018
Transportation Cessna CR-3, a racing aircraft designed in 1933 Curtiss CR-3, a racing aircraft designed in 1921 County Road 3 (disambiguation), several roads Loyang MRT station, Singapore, station code CR3
Other uses The royal cypher C III R (sometimes written as CR III) for Charles III Rex (Charles III, King) Crystal River 3 Nuclear Power Plant CR3, a postcode district in the CR postcode area