Clinically significant idiopathic macular pucker was observed in 11 patients aged 30 years or younger. In these patients, the tissue was well defined and fibrous in appearance, in contrast to the thin, cellophane appearance that is typical of macular pucker in elderly patients. Vitrectomy and epiretinal membrane peeling were performed in each case. Visual acuity improved after surgery in seven cases and worsened in one case, and follow-up data was not obtained in three cases. Recurrent membranes were noted in four cases, two of which detached spontaneously. Ultrastructural studies were performed on the removed specimens in each case. Myofibroblasts, myoblastic differentiation of retinal pigment epithelial cells and fibrous astrocytes, and new collagen formation were more common than in idiopathic macular pucker in older patients. The clinical and ultrastructural features of juvenile macular pucker reflect more rapidly changing, contractile tissue compared with the usually more quiescent features in series involving older patients.