From Jan. of 1990 to Dec. of 1992, we have experienced three cases of multiple primary malignant neoplasms originated from different histogenesis, in the Department of Orthopedic Surgery of Korea Cancer Center Hospital. Liposarcomas, malignant fibrous histiocytoma were combined with renal cell carcinoma, mucinous cystadenocarcinoma of ovary or prostatic cancer. With Moertel's classification, synchronous tumors were found in 2 cases and metachronous in 1 case. Synchronous tumors were 2 liposarcomas-renal cell carcinoma or mucinous cystadenocarcinoma of ovary. Metachronous tumors were malignant fibrous histiocytoma-prostate cancer. We couldn t find any family history among them. The causes of these multiple malignancies were considered as the individual predilrection to tumors.