In 1982, nationwide registration of obstetric data was instituted in The Netherlands with about 70% of all Dutch hospitals participating. The resultant data from 57 819 singleton pregnancies in vertex or breech presentation at delivery was studied. The vertex and breech groups were compared. The proportion of breech presentations relative to vertex presentations was greater in low gestational age infants and those of low birthweight. After correction for gestational age and birthweight, the perinatal mortality was higher in the breech groups than in the vertex groups. Congenital malformations occurred more frequently in the breech group but, even after exclusion of infants with congenital malformations, perinatal mortality remained higher in the breech group at any gestational age. Caesarean section was more frequently performed in the breech group than in the vertex group but did not appear to improve the outcome of breech presentation. It is possible that breech presentation is not coincidental but is a consequence of poor fetal quality, in which case medical intervention is unlikely to reduce the perinatal mortality associated with breech presentation to the level associated with vertex presentation.