In the current study, the uterine fluid level of human decidua-associated protein (hDP) 200 was measured in 80 women with abnormal uterine bleeding and normal histology. In 20 women the level of hDP200 was also correlated with the endometrial thickness measured by transvaginal ultrasonography. The results demonstrated the same distribution and similar levels of uterine fluid hDP200 throughout the menstrual cycle as in regularly cycling women, with no correlation between the levels of hDP200 and the endometrial thickness. Thus, the test for uterine fluid hDP200 could serve to discriminate between benign and pathological examinations of endometrial biopsies in women of reproductive age, women with abnormal uterine bleeding and benign conditions of the endometrium. Very low levels of hDP200 are indicative of endometrial hyperplasia or carcinoma.