An 18 years follow-up study of 105 males born in 1962/63 with birthweight less than or equal to 2 500 g was made at the military draft board examinations in 1981. The medical and psychological tests were compared to the tests of the total cohort of 35 728 Norwegian conscripts. The early neonatal mortality in the study was 15.2%, and of those examined at 18 years of age was 6.7% unfit for military service, compared to 6.2% in the total cohort. Ten organ systems were analyzed, significantly increased frequency of unfitness being found only for the vision. Intelligence testing was done on 71 of the studied subjects, and the mean was the same as the national average. Children with weight-for-date centile less than 10 at birth had the same general intelligence at 18 years as the national average. However, the weight and height at adult age were significantly correlated to the weight-for-date at birth. The study indicates that those low birthweight children who survived the neonatal period in the beginning of the nineteen-sixties, were except for stature and minor defects of vision, indistinguishable from those of normal birthweight at the age of eighteen.