This is a clinicopathologic study of 62 cases of persistent hyperplastic primary vitreous (PHPV). The cases were divided into two main groups. Group 1 consisted of 55 unilateral cases not associated with any systemic abnormalities, including 36 eyes (58%) which were considered "pure cases" (Group 1A) and 19 (31%) which disclosed other ocular abnormalities in addition to PHPV (Group 1B). Group 2 consisted of 7 (11%) bilateral cases of PHPV accompanied by other ocular and systemic malformations. The most common presenting clinical signs are leukocoria, microphthalmia and cataract. The main histopathologic features of this condition are outlined, including those responsible for the disastrous results to the eye (retinal detachment, glaucoma, phthisis bulbi). Several clinical entities, usually mistaken for or associated with PHPV, such as retinoblastoma, congenital cataract, retinal dysplasia, trisomy 13 syndrome, and falciform retinal folds are discussed briefly.