Sarcomas in the uterine corpus are rare and usually difficult to diagnose preoperatively. A series of cases were investigated to reveal their cytological and pathological aspects. All 49 uterine sarcomas diagnosed at Saiseikai Utsunomiya Hospital during the past 17 years were surveyed. Uterine corpus sarcomas accounted for 4.7% of malignant uterine corpus tumors and 1.1% of uterine corpus mesenchymal tumors. In descending order of frequency, carcinosarcomas, leiomyosarcomas, and endometrial stromal sarcomas accounted for 24 (49%), 14 (29%), and 8 (16%) of cases, respectively. Excluding inadequate or untested cases, preoperative endometrial biopsy revealed malignant or atypical lesions in 19 (95%) of the carcinosarcomas and 4 (80%) of the endometrial stromal sarcomas. Leiomyosarcomas were not biopsied preoperatively except in one case each diagnosed as leiomyosarcoma and leiomyoma. By endometrial cytology, carcinosarcomas tested positive or suspicious in 82% of cases, exhibiting a clear tendency for heterologous and homologous subtypes to test positive and suspicious, respectively. In contrast, leiomyosarcomas and endometrial stromal sarcomas consistently tested negative except a suspicious case of high-grade endometrial stromal sarcoma. These results thus suggest that preoperative histopathological and cytological approaches may improve the accuracy of preoperative diagnosis.