In 783 patients from age 38 to 83 aspiration cytology of the endometrium was carried out and compared to microscopic findings of the endometrium from the curettages. The samples were obtained from women with post-menopausal and pre-menopausal bleeding and from women without bleeding prior to hysterectomy for various indications. In 49.% of the cases adenocarcinoma of the endometrium was detected, and in 4.2% of the cases pre-cancerous lesions such as adenomatous or atypical glandular hyperplasia of the endometrium and of the endocervix were observed.