Doctors need reliable data on outcome in order to help parents faced with difficult decisions about termination of an affected pregnancy or treatment after birth. To determine survival, health and lifestyle at the mean age of 30 years in a complete cohort of adults born with open spina bifida. Prospective cohort study. Well-documented cohort of 117 consecutive cases of open spina bifida whose backs were closed non-selectively at birth between 1963 and 1971. Survivors (age range = 26 to 33 years) were surveyed by postal questionnaire and telephone interview. The main outcome measures were the health, independence and lifestyle of the survivors in terms of living in the community, driving a car and working in open employment. Ascertainment was 100%. Sixty (51%) had died, mainly the most disabled. Of the 57 survivors, 84% had a cerebrospinal fluid (CSF) shunt, 70% had an IQ of 80 or more, 37% lived independently in the community, 39% drove a car, 30% could walk more than 50 metres and 26% were in open employment. However one-third (19) still needed daily care, three were on respiratory support, two were blind, two had diabetes mellitus, and one was on dialysis. Mortality, disability and achievement reflected the neurological deficit that had been recorded in infancy in terms of sensory level. Attainment and independence were reduced in those who had needed revision of CSF shunt. The survivors in this unselected cohort showed a wide range of outcome from apparent normality to very severe disability. This reflected both the extent of their original neurological deficit and events in the history of their CSF shunt.