Histologic examination of the prepuces removed from 78 consecutive patients with phimosis was performed during a 2-year period. In 15 cases (14.2%), the typical changes of lichen sclerosus et atrophicus (LSA) were found. A different, distinct histologic pattern of fibrosis was noticed in six patients (7.7%). Clinically, the two conditions were indistinguishable and presented as severe, nonretractable phimosis. The largest group of the patients (46.2%) had histologically normal prepuces, but clinically they too had severe phimosis. Since phimosis especially in young boys may regress spontaneously, and since on the other hand LSA may evolve into squamous cell carcinoma, we conclude that treatment of phimosis should be planned according to its histologic pattern and not according to its monotonous clinical appearance.