A total of 315 twin pregnancies delivered during a 12-year period are reviewed, first to assess the value of admitting the mother to hospital during the last few weeks of pregnancy, and secondly to analyse the perinatal mortality. Rest for the mother in hospital will prolong the pregnancy and increase the birth weight of the children significantly and will reduce the perinatal mortality. Some of the perinatal deaths occur in the neonatal period in a group of infants delivered before the end of the 35th week of gestation and, in almost all these cases, the cause of death is respiratory failure. If delivery takes place after the 35th week of gestation, perinatal death occurs mainly as intrauterine death. Possible causes and consequences are discussed.