In order to evaluate possible etiological factors and the natural course of 'idiopathic' preretinal fibrosis in young persons, nine consecutive patients with macular pucker diagnosed under the age of 50 years were examined. There were six women and three men with the mean age of 27.2 years (range 15-50) and the mean follow-up of 4.5 years (range 1.5-10). The initial visual acuity varied from 0.25 to 1.0. The preretinal membrane was either central or paramacular. In two eyes the process was probably congenital (retinal hamartoma), one was postinflammatory (retinal vasculitis), and one was associated with sclerosis of the anomalous macular arterioles. In the others no causative factors were discovered. In seven of the nine eyes both the visual acuity and the fibrotic process remained stable, in one eye the vision improved, and in one eye deteriorated. It seems that most young persons with 'idiopathic' preretinal fibrosis of the macula can be followed up without surgical removal of the membrane.