All forty-two breech infants delivered by caesarean section before the 37th gestational week since Jan. 1, 1975, were followed up prospectively. Outcome in this group was compared with that for all forty-eight breech infants delivered vaginally in 1971-74, before the introduction of routine caesarean section. Delivery by caesarean section significantly reduced the frequency of severe prolonged asphyxia, and neonatal mortality was reduced from 14.6% to 4.8%. At 12 months of age 24% of those delivered vaginally had developmental or neurological abnormalities compared with 2.5% of those delivered by caesarean section.