The overall 1-year survival rate of 261 infants born at 500 g-999g over a 7-year period was 46%. The survival rate of the 220 inborn infants, corrected for birth defects, would have increased from 47% to 57% if delivery room deaths were excluded and to 62% if postneonatal deaths had also been ignored. Survival improved progressively with increasing 100g weight groups. The disability rate in the 108 survivors who were at least 2 years old corrected for prematurity was 28% with little variation between the 100g weight groups. There were no significant trends in annual perinatal mortality, 1-year survival and disability rate in survivors over the study period for the inborn population. The male infants had significantly lower normal-survival rate than the female infants. Small-for-gestational-age infants, comprising 11% of the inborn group, had significantly better survival but a higher disability rate. Multiple births had significantly lower survival and normal-survival rates than had singleton births. Infants whose mothers were transferred for delivery at the perinatal centre before onset of labour had a significantly better survival rate than those whose mothers had 'booked' and those who were transferred in labour.