Our study is a trial to evaluate the endobrush as a method for monitoring the endometrium during tamoxifen treatment. An anatomopathological study of the endometrium was carried out in 189 patients treated by tamoxifen (between February 1995 and October 1997). In all patients vaginal ultrasound examination revealed an endometrial double layer thickness of more than 8 mm, In 39 cases cytological sampling was impossible (cervical stenosis, pain); in 150 patients cytology was performed, followed by hysteroscopy and curettage, In 145 patients the correlation between cytology and histology was good (141 benign lesions and 4 endometrial cancers). In 5 patients a false-positive diagnosis was made (4 atypia, 1 cancer). (C) 1998 Elsevier Science Ltd. All rights reserved.