Most multiple pregnancies are diagnosed, but early diagnosis still presents some problems. Congenital malformation is commoner in multiple pregnancies, usually without concordance, which complicates decisions about pregnancy termination. Because of the higher perinatal mortality rates, women with multiple pregnancies should be offered extra antenatal care, with the specific objectives of early diagnosis and timely treatment of pre-eclampsia, preterm labour and growth retardation. If growth retardation affects only one fetus, intervention must be carefully judged. Measures such as bedrest, fetal monitoring and elective operative delivery are reviewed, and no evidence of benefit is found from their routine use. However, such interventions are valuable in selected cases.