Abdominal muscle deficiency, urinary tract abnormalities, and cryptorchidism are the three major features of the prune-belly syndrome, also referred to as triad syndrome or Eagle-Barrett syndrome. The etiology is unclear and the pathogenesis a subject of continuing debate. Clinical and pathologic experience with seven cases of prune-belly syndrome is reviewed. Findings indicate that the urogenital anomalies can be attributed to a functional urethral obstruction which in turn is the result of prostatic hypoplasia. The histology of the abdominal wall is that of atrophy-ie, the degeneration of already formed muscle--and not of primitive muscle. This observation supports the theory that the abdominal muscle hypoplasia is a nonspecific lesion, resulting from fetal abdominal distension of various causes. Transient fetal ascites may be an important feature of the prune-belly syndrome.