Among 30 patients examined, posterior hyperplastic primary vitreous was monocular in 25 and binocular in five. Poor vision and strabismus were the most common presenting complaints. All patients had vitreous membranes usually extending from the disk toward the equatorial zone. In 70% of the affected eyes, the vitreous membranes were associated with a radial retinal fold. Macular function was disturbed in 70% and retinal detachment was observed in 45% of the eyes. One extensive retinal detachment was successfully treated by scleral buckling; another detachment, limited to the posterior pole, responded to sectioning of a vitreous band with scissors.