Objective To examine the prognosis of idiopathic choroidal neovascular membranes in patients younger than 50 years of age at the time of diagnosis. Design Retrospective noncomparative case series. Participants Eighteen consecutive patients from a university clinic (20 eyes) with idiopathic choroidal neovascularization in the macular area. All patients diagnosed between 1979 and 1996 were included; follow-up time varied from 5 to 187 months (mean, 55 months). Intervention Treatment was conservative. All patients were informed about argon laser photocoagulation, but in the majority of cases, patients were not encouraged to undergo such treatment. Treatment was given on patient’s request. Main outcome measures The dimensions of the choroidal neovascular membrane and its distance to the foveola were determined by computerized image analysis and their correlation with final visual acuity determined. Results Fifteen (75%) of the 20 eyes retained a visual acuity of 20/60 or better. In ten eyes (50%), acuity was 20/25 or better. Six eyes had been treated with laser photocoagulation; only one had a membrane located 200 μm or more from the foveola at the time of treatment. The outcome for treated eyes was no better than for untreated eyes, although the two groups were not directly comparable. In no eye did an initially juxtafoveal or extrafoveal membrane continue to grow under the foveola. Conclusions The prognosis of idiopathic choroidal neovascularization was much better than reported previously for eyes with choroidal membranes associated with age-related macular degeneration. A conservative treatment regimen should be considered. The authors have no reason to believe that laser photocoagulation would have improved the outcome in the nontreated eyes.