One hundred thirty-one patients with epidermal nevi are reviewed. The commonest site of involvement was the head and neck, and 13% of patients had widespread lesions. Ages of onset ranged from birth to 14 years. A spread beyond the original distribution was noted in 37% of patients. Many clinical patterns occurred, including eight cases of inflammatory linear verrucous epidermal nevus. A variety of other cutaneous abnormalities were found. Biopsies were performed in 41 cases. Three patients developed secondary tumors. One hundred nineteen of the patients were assessed for the presence of abnormalities in other organ systems. One or more abnormalities were demonstrated in 33% of patients, and in 5%, five or more abnormalities were detected. This study indicates that patients with epidermal nevi are at significant risk of having other abnormalities and warrant detailed initial assessment and close follow-up.