Transvaginal sonography has found increasing application in evaluating patients planned for endoscopic surgery. Over a 4-year period, from 1988-1992, 376 patients underwent endoscopic evaluation for pelvic pain, pelvic masses, infertility, abnormal bleeding, endometriosis, and suspected ectopic pregnancy. The study encompasses an initial retrospective and subsequent prospective study. The author performed transvaginal sonography in 49.7% of the patients in the preoperative evaluation. A prediction of the surgical findings based on pelvic examination alone and in combination with vaginal sonography was undertaken. Transvaginal sonography was far superior to pelvic examination with an overall sensitivity of 81% with a 98% specificity in predicting the abnormalities to be encountered. The author now uses transvaginal sonography routinely in the evaluation of patients preoperatively. Endoscopy has thus progressed from a diagnostic procedure to a confirmatory procedure with the anticipated operative procedure being more accurately predicted. This affords better scheduling of operating time, equipment, and personnel requirements. Also, informed consent in preoperative counseling is greatly enhanced in these women. The author recommends that physicians consider obtaining transvaginal sonography as an integral part of the preoperative evaluation of patients. As a result, the prediction of pathology encountered, counseling of patients, and the planning of the surgical procedure are greatly enhanced.