All twins delivered at Aker Hospital during the years 1987-88 and 1990-93 were registered in this study. However, from 1990 onwards, all mothers bearing twins received special antenatal care after the 28th week of pregnancy. This care consisted of Doppler sonography of the umbilical artery and estimates of foetal weight by ultrasonography at each visit. Comparing the foetal outcome in the years 1987-88 with that in 1990-93, it was found that the perinatal mortality rate decreased from 5.4% to 2.2% and the Apgar score at 5 minutes of age improved for both twins. Ultrasound foetometry and Doppler sonography are valuable tools for antenatal surveillance of twin gestation.