We reviewed the Mayo Clinic records of 56 patients who underwent operation for cardiac myxoma and 29 cases in which cardiac myxoma was found at autopsy. Five patients had a "complex" of unusual findings including multiple pigmented skin lesions (lentiginosis), myxoid fibroadenomas of the breast, skin myxomas, and primary pigmented nodular adrenocortical disease (a cause of Cushing's syndrome). Four of these five patients had multiple cardiac myxomas. Three of the four patients who underwent surgical excision of the cardiac myxomas had recurrent myxomas (the only recurrences in our series), and one of these patients had a second recurrence. The occurrence of multiple and recurrent myxomas in patients with the complex was significantly (p less than 0.001) higher than in our 80 patients with sporadic myxomas. The world literature was searched for cases of cardiac myxomas with the unusual associations of the complex, and also for familial, multiple, and recurrent myxomas. A group of patients were identified who had unusual biologic behavior including early development of myxomas, atypical myxoma locations, and a high risk for the development of recurrent myxomas. For these patients, we recommend a thorough search for multiple tumors at operation, close postoperative follow-up, and careful screening of family members.