Objectives. Sonohysterography (SHG) has been proposed as a useful tool for the surveillance of the endometrium in patients receiving tamoxifen. This study aimed to assess the value of SHG in asymptomatic patients who would have been biopsy candidates because of abnormal transvaginal ultrasound (TVUS) results. Methods. The study population included postmenopausal breast cancer patients receiving adjuvant tamoxifen who had asymptomatic abnormalities at TVUS (endometrial thickness greater than or equal to 8 mm or endometrial echo not adequately visualized). SHG was performed with an Aloka SSD 680 system using a 5-MHz vaginal probe, with sterile saline solution as contrast medium. Results. Forty-one patients entered the study. A regular endometrial echo was identified by SHG in 9 patients (21.9%). Histology was obtained in the remaining 32 patients with positive (n = 27, 65.8%) or unsuccessful (n = 5, 12.2%) SHG. Benign polyps (n = 15, 36.6%) and endometrial atrophy (n = 14, 34.1%) were the most common findings; 3 patients (7.3%) had simple hyperplasia. Conclusions. Breast cancer patients with asymptomatic, tamoxifen-associated TVUS abnormalities have little additional benefit from SHG. More than 2/3 remain candidates for biopsy, which usually yields benign or insignificant findings, (C) 2000 Academic Press.