The incidence, treatment and immediate course in infants with postnatal apnoea were studied. Information on all infants born in Sweden in 1985 with a low Apgar score (3 or less at 1 min or 6 or less at 5 min) was collected from the midwife and from the baby's chart. Of the 97,648 live births, 1633 (1.7%) had a low Apgar score. The risk increased with decreasing birthweight and with severe malformations. Before delivery, 19% of the low-Apgar-score infants were not expected to require resuscitation. Eighty percent of the ventilated infants were satisfactorily ventilated by bag and mask; the remainder were intubated. Of the ventilated infants, 78% developed spontaneous breathing within 10 min after birth and 89% within 20 min. Routine intubation or administration of buffer in cases of postnatal asphyxia had no influence on the time to onset of regular spontaneous breathing.