We describe a family in which lentigines were present in the index patient, in three of her seven siblings, in their mother, and in a niece (the daughter of an affected sister). Cutaneous myxomas were present in the index patient, in two of her brothers, and probably in their mother. In addition, the index patient had two cardiac myxomas. multiple myxoid mammary fibroadenomas, and the Cushing syndrome, and an affected brother had acromegaly caused by a growth hormone-secreting tumor of the pituitary gland. Thus, at least one manifestation of the complex of myxomas, spotty pigmentation, and endocrine overactivity has occurred in three successive generations of this family. Both male and female family members were affected, and 5 of the 11 children of affected persons had the disorder. The karyotypes of two affected persons were normal. These observations are consistent with mendelian dominant inheritance of the syndrome.