The aim of the study was to define the role of sonography as a separate method in prediction and confirmation of ovulation. The growth of the follicle over the period from the 10th to the 17th day of menstruation was sonographically followed-up in 63 spontaneous and induced cycles. It was found that sonography was a quick and simple method. As separate method it can be used for the confirmation of ovulation, prevention of hyperstimulated ovarian syndrome and determination of the best time for artificial insemination. In combination with the other procedures it is convenient for prediction of ovulation.