The authors report the case of a very large, obstructive malignant melanoma (MM.) of the prepuce, encasing all of the distal extremity of the penis, and discovered at a late metastatic stage (regional lymph node metastasis). Palliative treatment, consisting of partial penectomy associated with a complementary induction and maintenance chemotherapy did not achieve any objective response at one year. MM. of the penis are rare urological tumours, including MM of the penis and MM of the male urethra (exclusively mucosal involvement). The diagnosis of MM of the penis must be considered in any case of black or brown lesion of the glans, which is the most frequent site. The prognosis is determined by the clinical stage (BRACKEN and DIOKNO classification) and by the depth and level of tumour invasion (BRESLOW index and CLARK's degree of dermal invasion). The 5-year survival is inversely proportional to the tumour thickness. The treatment of MM of the penis is surgical; the extent of resection and the indication for lymph node dissection depend on the patient's age, sexuality, and the stage of the disease and depth of tumour invasion.