Mastocytosis is a disease characterized by excessive accumulation of mast cells in different tissues and symptoms caused by the release of mast cell mediators. The skin is frequently directly involved in mastocytosis. The disease is rarely seen in other members of the subjects' family; only 49 cases of familial mastocytosis have been reported. Familial mastocytosis associated with hearing loss may represent a newly described inherited entity. We describe a brother and sister exhibiting skin mastocytosis and neurosensory deafness, associated with a history of hearing loss in their father's family. The appearance of the mast cell disease in two siblings, who presented with similar clinical features represents a familial form of mastocytosis; the association with an inherited form of deafness may constitute a new syndrome. Our patients show several features similar to some previously reported cases but different insofar that additional congenital defects and mental retardation are absent.