This paper compared the use of a transvaginal scanning approach with the conventional transabdominal scanning method. In study I, 15 patients with previous suboptimal abdominal ultrasounds were evaluated in subsequent cycles with both the transabdominal and the transvaginal techniques. With the transvaginal method, improvement was observed in 13 patients (87%). Study II compared both the transabdominal and transvaginal ultrasound measurements of follicle number and size with surgical findings. A high correlation (r = 0.914, P less than 0.001) was demonstrated between the number of follicles visualized by transvaginal sonogram and the number of follicles aspirated. A significant correlation (r = 0.639, P less than 0.001) was also observed between follicular fluid volume and the mean ultrasound follicle diameter determined transvaginally.