Résumé : The authors describe the case of a 64-year old man who presented with an asymptomatic brown macula on his glans penis that had appeared about 18 months earlier. Dermoscopy analysis demonstrated a prominent, wide and irregular pigment network, which stopped abruptly at the periphery of the lesion. A diagnostic biopsy showed the characteristics of a melanoma in situ .The patient was referred for partial surgical excision of the glans. No recurrence or metastasis occurred during the two years after the operation. Melanoma in situ of the penis is very rare in dermatologic literature. Early diagnosis is of paramount importance because its prognosis is very poor. Early systematic use of dermoscopy may be useful for the differential diagnosis of pigmented mucosal lesions, which include mucosal melanosis and other benign melanoses of genitalia.