The aim of the study was to estimate of efficiency of endovaginal ultrasonography in diagnosis of ovarian endometriosis. The study was performed in 59 women with ovarian tumors. Ultrasound examinations were performed with Aloka 2000 using 5.0 MHz transducers. The endovaginal ultrasonography is very useful in diagnosis of ovarian endometriosis, showing sensitivity--90%, specificity--68%, positive predictive value--75%, negative predictive value--86%. Ultrasound examination is an important tool in noninvasive diagnostic procedure of adnexal pathology.