This article illustrates the different appearances of benign ovarian and paraovarian masses at endovaginal sonography. A retrospective study was performed of the records for 118 patients with 140 surgically proved benign adnexal masses, including dermoid cysts (n = 27), endometriomas (n = 40), epithelial inclusion cysts (n = 14), serous cystadenomas (n = 11), mucinous cystadenomas (n = 14), fibromas (n = 11), cystadenofibromas (n = 12), paratubal cysts (n = 5), hydrosalpinges (n = 3), and tubo-ovarian abscesses (n = 3). Preoperative diagnosis was made in 96% of the dermoid cysts on the basis of a hyperechoic attenuating component or multiple small horizontal interfaces and in 100% of uncomplicated fibromas on the basis of a hypoechoic attenuating mass. There was an overlap among the endovaginal sonographic appearances of the other condition.