Sonohysterography is a simple ultrasound (US) procedure that may be used to evaluate the endometrium. The technique involves placement of a 5-F catheter into the endometrial canal with subsequent instillation of sterile saline solution under US guidance. Fifty patients successfully underwent sonohysterography because of apparent abnormal endometrial thickening at transvaginal US, a nonspecific finding. Patients tolerated this procedure well, and no complications were encountered. In the 39 patients who proved to have endometrial pathologic conditions, sonohysterography demonstrated focal processes (polyps, carcinoma, hamartoma) in 15, diffuse processes (hyperplasia, secretory endometrium) in 21, and both focal and diffuse pathologic conditions in three. If a focal process can be delineated, a visually directed biopsy may be necessary. However, if the process is diffuse, a blind aspiration biopsy may be performed on an outpatient basis. In the majority of patients, the diffuse or focal nature of the disease could not be predicted on the basis of initial transvaginal US. Because sonohysterography allows distinction between diffuse and focal abnormalities, it provides physicians with a cost-effective way to plan the next step in case management.