D50, D-50 or D 50 may refer to: * D50 (radiotherapy), the half maximal inhibitory dose, representing the dose of light or ionising radiation that is required for 50% inactivation of a tumor cell population * the ICD-10 code for Iron deficiency anemia * An intravenous sugar solution of 50% dextrose * JNR Class D50, a pre-war Japanese steam locomotives class related to the D60 steam locomotive class * New South Wales D50 class locomotive, a NSWGR steam locomotive * Lancia D50, a Formula One racing car that competed between 1954 and 1956, winning Juan Manuel Fangio the 1956 World Driver's Championship. * CIE Standard Illuminant D50, a lighting standard used in colorimetry, and also in graphic design as a white point * Nikon D50, an entry-level digital SLR camera * Roland D-50, a digi