Sarcoma of the uterus is very rare malignant tumor originating from uterine muscle or connective tissue. We have experienced 20 cases of uterine sarcoma from January 1991 to June 1998. The results were as follows: 1. The pathologic types were 13 cases(65.0%) of leiomyosarcoma, 5 cases(25.0%) of malignant mixed Mullerian tumor, 1 case of rhabdomyosarcoma, and 1 case of angiosarcoma. 2. The average age and parity was 50.2 and 3.7. The chief complaints were irregular vaginal bleeding(35.0%), lower abdominal pain(25.0%), and abdominal mass(25.0%). 3. Nine cases(45.0%) were FIGO stage I, 1 case(5.0%) was stage II, 6 cases(30.0%) were stage III, and 4 cases(20.0%) were stage IV. 4. The survival was from 1.5 months to over 130 months(median 16.5 months), and there was no correlation between survival and FIGO stage or pathologic type. The correlation between survival and number of mitotic figure was incalcurable. 5. CA 125 levels were serially measured as a tumor marker in monitoring patients and the positive rate was 40%. Further study was needed to make a conclusion for usefulness of CA 125 as a tumor marker.