A woman was operated on for a nonepithelial malignant tumor of the left leg and subsequently, for an epithelial carcinoma of the right breast and a borderline malignant tumor of the right ovary. She also developed a giant cavernous hemangioma that caused disseminated intravascular coagulation syndrome, which necessitated a left trisegmentectomy of the liver. Her family history suggested a hereditary predisposition to diverse malignant neoplasms, and also to giant cavernous hemangioma of the liver. Immunological evaluation disclosed selective inhibition of natural killer cell activity. Hormonal and hereditary factors are discussed in relation to the development of multiple primary tumors and giant cavernous hemangioma of the liver.