Every practitioner undoubtedly has been consulted on more than one occasion by a patient presenting a rather persistent plaque of dermatitis on the glans penis. To the patient, such a lesion is a source of considerable worry and concern. The lay person is inclined to think primarily of two groups of diseases as possible causes for his penile lesion—one is venereal disease and the other cancer. With the physician rests the obligation of establishing the diagnosis, instituting appropriate therapy, and reassuring the patient. The different dermatoses which may affect the penis are indeed numerous and it is not our intention to discuss them all. Careful clinical examination, together with conscientious history taking and adequate knowledge of the possible diagnoses, plus the results of appropriate laboratory studies are usually sufficient to establish a diagnosis in the more evanescent of these lesions—primary syphilis, chancroid, scabies, mycotic infections,