OBJECTIVE this study compares endovaginal sonography to the transabdominal ultrasound in terms of their accuracy in the measurement of the uterus and ovaries. TYPE: prospective study. METHODS São Paulo, SP, Brazil. METHODS Forty-nine women were included in the study in order to assess the clinical suspicion of pelvic mass or because they had vaginal bleeding in initial gestation. The patients were submitted to transabdominal sonography and later to endovaginal ultrasound (5.0mHz transducer). Uterus and ovaries were measured. RESULTS the volume of 27 left and 29 right ovaries was measured. Echographic hysterometry was performed in 49 women and statistically compared. The Wilcoxon rank sum test failed to show any significant difference between the two sonographic techniques in the measurement of uterus and ovary volume. CONCLUSIONS endovaginal ultrasound presents several advantages over transabdominal scanning. Patient's discomfort is minimum because vesical repletion is not called for. Imaging resolution is magnified and morphologic details are clearly seen because the transducer is in close contact with pelvic viscera. Results do not evidence any significant difference in the uterine measurements with either method, and the statistical difference in ovarian volume was not significant either.