An 80-year-old white woman developed vulvar melanosis and malignant melanoma of the labia majora and clitoris and underwent a simple vulvectomy. She subsequently developed melanosis of the urinary bladder and presented 3 years later with multifocal malignant melanoma involving the vagina, urethra, and urinary bladder in a background of extensive melanosis with variable degrees of atypia. She underwent radical surgery but died 18 months later with liver metastases and liver failure. Malignant melanoma is uncommon in the vulva and vagina and is rare in the urinary bladder. This case illustrates the previously described association between melanosis and malignant melanoma. The unusual features are the widespread distribution of the melanosis (vagina and bladder) and the subsequent development of multifocal malignant melanoma.