In patients with endometrial cancer, preoperative identification of certain poor prognostic factors is helpful in planning therapy. To determine the place of cervico-vaginal cytology in this respect, we have studied the relationship between cervico-vaginal cytology and the well-known prognostic factors of endometrial cancer such as grade, myometrial invasion, peritoneal cytology, stage and histological subtype. A hundred and sixty two patients, all of whom underwent surgical therapy in our clinic, were included in this study in order to correlate the cytological results with the pathological findings. Cervico-vaginal cytology was negative in 88 patients (54%), suspicious in 26 patients (16%) and malignant in 48 patients (30%). Twenty four per cent of cases with adenocarcinoma and adenoachantoma, and fifty two per cent of patients with adenosquamous carcinoma, papillary adenocarcinoma and clear cell carcinoma had positive cervicovaginal cytology (p < 0.001). Seventy four per cent of patients with negative cervicovaginal cytology had grade I tumor, while 5% of patients with negative cytology had grade III tumor. On the other hand, only 9% of patients with positive cervico-vaginal cytology had grade I tumor, while 55% had gade III tumor (p < 0.001). 8% of patients with inner 1/2 myometriaI invasion had positive cytology, whereas 51% of patients with 1/2 outer myometrial invasion had malignant cells in their smear (p < 0.001). As for the staging of the endometrial cancer according to FIGO, 19% of patients with Stage I disease had positive cervico-vaginal cytology while 60% of patients in Stage II and 66% of patients in Stage III-IV had positive cytology (p < 0.05). The majority (72%) of patients with positive cervico-vaginal cytology also had positive peritoneal cytology. In addition, peritoneal cytology was positive in only 15% of patients with negative cervico-vaginal cytology (p < 0.01). Therefore positive cervico-vaginal cytology was associated with deeper myometrial invasion (p < 0.001), high postoperative tumor grade (p < 0.001), positive peritoneal washing (p < 0.01) and more advanced stage by FIGO (p < 0.05). These data clearly suggest the usefulness of cervico-vaginal cytology in the preoperative assessment of the known prognostic factors of endometrial cancer such as grade, myometrial invasion, histological subtype, stage and peritoneal cytology.