Recent studies have shown that macrophage colony-stimulating factor and its receptor c-fms protein are significantly overexpressed in endometrial and ovarian cancers. In the present study, we analyzed the steady-state levels of c-fms mRNA in benign and malignant endometrial tissues by Northern and slot blot analyses. The relative levels of c-fms mRNA were quantified by using a hybridization signal for each sample on Northern blot analysis. Slot blot analysis was used to further quantitate the relative increase in c-fms mRNA in malignant specimens compared to benign specimens. Correlation of c-fms expression in the endometrial cancers was made with traditional prognostic indicators. Secretory endometrium had low levels of c-fms mRNA, whereas the endometrial cancers had the highest levels. Proliferative and hyperplastic endometrium values were intermediate. Comparative assessment of c-fms expression in endometrial cancer relative to other prognostic factors demonstrated greater expression of c-fms in specimens from patients with abnormal DNA ploidy, high-grade lesions, and possibly extrauterine metastases. Our study confirms the overexpression of c-fms in endometrial cancer and demonstrates a positive correlation between the steady-state mRNA levels of c-fms and other select adverse prognostic indicators.