With the advent of B-mode transvaginal sonography, new opportunities are presented to better define ovarian lesions. Since its development in 1966, the transvaginal ultrasound continues to be an essential component in the diagnostic work-up of adnexal masses. This study reviewed the histopathological diagnoses of 387 patients who underwent surgery for removal of a benign ovarian cyst at our institution and compared it with the results of the patient's pre-operative ultrasound examinations done at the ultrasound section. After statistical analysis, this study showed that the B-mode transvaginal ultrasound is accurate in diagnosing the majority of benign ovarian cysts. Although it is more sensitive and specific for some types of benign ovarian cysts over others, it continues to be an important tool in the initial work-up of an ovarian cyst.