We report on 2 patients with mental retardation and bullous dystrophy, macular type. The observation of the condition in a male and his maternal uncle is consistent with recessive X-linkage. Due to the rarity of the condition, nosologic definition was difficult before the birth of the propositus. The clinical picture in the two patients described, characterized by mental retardation, dwarfism, microcephaly, alopecia, bullous dystrophy macular type, hypogenitalism, is very much like the one observed in the patients, all males, belonging to the only other family reported to date. The recent localization of the bullous dystrophy gene in the Xq24-qter segment opens the possibility of prenatal diagnosis.