A study of 79 twin pregnancies was conducted between 1973 and 1976 with particular reference to the use of ultrasound and hormone analysis. There were 17 perinatal deaths, n perinatal mortality rate of 107 per 1000 deliveries. The contributing factors were antepartum anoxia (40%), prematurity (30%), congenital abnormalities (18%), and obstetric trauma (12%). During the period of study there was a complete change in the method of confirming twin pregnancies, ie, in 1973, 84% were confirmed by x-ray and in 1976, 86% by ultrasound. About 40% were diagnosed at 28- weeks' gestation or earlier. The ranges (mean ± 2 SD) for human placental Iactogen (hPL) and urinary estrogens have been established for twin pregnancy, and the value of these measurements in the antenatal management of twin gestations is discussed.