We describe a family with the unusual association of Cowden's disease and Bannayan-Riley-Ruvalcaba syndrome. The father has characteristic mucocutaneous features that are palmoplantar keratoses, multiple facial papules, oral papillomatoses, lipomas, and vitiligo with involvement of the thyroid and digestive tract. The son presents with pigmented macules of the penis, macrocephaly, and a lipoma that are typical for Bannaya-Riley-Ruvalcaba syndrome. Recent studies have demonstrated that these 2 diseases are allelic disorders at the PTEN locus on chromosome 10q.