The aim of the present study was to evaluate estrogen receptor (ER) and progesterone receptor (PR) expression in the glandular epithelium and stroma of benign and malignant endometrial polyps of postmenopausal patients. A total of 1,050 females underwent surgical hysteroscopy at the Professor Dr José Aristodemo Pinotti Women's Hospital, Center for Integral Attention to Women's Health of the State University of Campinas, between January 1998 and December 2008. Of the total number, 390 postmenopausal females with endometrial polyps were included in the study. Polypoid lesions were histologically classified as benign lesions (endometrial polyps and polyps with non-atypical simple hyperplasia or non-atypical complex hyperplasia) and premalignant and malignant lesions (polyps with atypical simple hyperplasia or atypical complex hyperplasia and carcinomatous polyps). ER and PR expression was evaluated by immunohistochemistry according to cell staining, intensity of nuclear staining and final score. The final score for receptor expression was compared between the benign and premalignant/malignant polyps. The prevalence of malignancy in endometrial polyps was 7.1% and was associated with postmenopausal bleeding. Only the final score for ER expression in the stroma of endometrial polyps was higher in the benign group than in the premalignant/malignant group, and this difference was significant. However, no difference was identified in PR expression. In addition, the risk of malignancy in endometrial polyps was significantly higher when the expression of ER and PR was negative in the stromal component of the polyp (P< 0.01). The malignancy of endometrial polyps was also associated with a low expression of stromal ER, however,