The study includes all infants in a Danish county born 1982-87 considered at risk of acquiring retinopathy of prematurity (n = 411; 178 girls, 233 boys). 325 had birthweight (BW) less than or equal to 1750 g and/or gestational age (GA) less than or equal to 34 weeks. The remaining referrals were on account of functional immaturity/significant oxygen treatment (n = 86). With a median onset age of 6.5 weeks (range 5-9 weeks) ROP was recorded in 63 infants. A negative correlation (r = -0.34) between GA and ROP onset age suggested a later onset in the very immature infant. ROP appeared in 60% of those born at GA less than or equal to 28 weeks (n = 30) and in 50% of survivals with BW less than or equal to 1000 g (n = 20). With BW and GA beyond the limits of 32 weeks and 1750 g only 5 cases of ROP were observed. Out of the 14 infants with at least stage 3 ROP 6 became blind in both eyes after few months (GA at delivery 25-31 weeks/BW 920-1595 g). All considered, 57 of the 63 with ROP showed spontaneous regression, however, leaving myopia of prematurity in 8 subjects.