The goal of this study was to evaluate the cytomorphologic features of histologically confirmed uterine papillary serous carcinomas (UPSC) of the endometrium. We reviewed cervicovaginal smears from 12 patients with UPSC who had done their cervical smears at six months to a year earlier before the time of diagnosis; nine smears (75%) were diagnosed as positive for malignancy and three smears (25%) were diagnosed as negative. The cervical smears of patients with UPSC revealed frequent papillary clusters that were composed of large pleomorphic tumor cells with prominent nucleoli in a background of necrosis. Other findings revealed from the tests were relatively frequent single malignant cells and bare nuclei. Although the Pap smear is not a sensitive screening test for endometrial carcinoma, we could depend on it to reveal the cytologic features of UPSC which are fairly characteristic and reliable for a preoperative diagnosis of UPSC. Preoperative identification of this poor prognostic variant of endometrial carcinoma may influence the surgical management of these cases and the choice of adjuvant therapy.