Twin-twin transfusion is a condition that was previously associated with close to a 100% perinatal mortality. Recent reports suggest that a survival rate of about 60% can be achieved with serial amniocentesis and modern neonatal care. However, it is now apparent that the survivors of this condition have multisystem complications that can result in neonatal mortality and long-term morbidity. Fourteen cases of twin-twin transfusion were examined to determine the antenatal findings that may predict the postnatal outcomes of these infants. The overall survival was 61% (17 of 28). The mean gestation at diagnosis was 23.0 weeks (range 18-34 weeks) and the mean gestation at delivery was 29.0 weeks (range 23-37 weeks). The mean number of amniocenteses was 2.9 and the average total volume of amniotic fluid removed was 6,114 mL. Different patterns of complications were seen in the donor and recipient twins. Hypertrophic cardiomyopathy affected 9 of the recipient twins. Anuria/oliguria was found in 4 of the donor twins and none of the recipients. Periventricular leukomalacia was found in 8 twins and 7 also had mild ventriculomegaly; of the surviving 17 twins, 5 had either periventricular leukomalacia, mild ventriculomegaly or both. Amniotic fluid leakage and perforation of the intervening membrane subsequent to serial amniocentesis were seen in 5 cases. Severe intrauterine growth retardation and abnormal cardiotocographs were a common feature. These complications directly resulted in neonatal mortality and long-term morbidity in the survivors. Not all complications were detected antenatally and the severity was not able to be anticipated.