In experimental studies, an increase of the ovarian blood flow was found during cycle stimulation. In this study, the authors performed transvaginal pulsed Doppler measurements of the ovarian arteries in stimulated cycles before and after follicle puncture. Four days before follicle puncture, high flow velocities in systolis were found compared with diastolis. Toward the day of embryo transfer, a marked increase of the diastolic blood flow velocity was observed. In patients with high endocrine response, the pulsatility index (PI) was significantly lower compared with that of patients with low endocrine response. The technique of transvaginal pulsed Doppler measurements offers the possibility to study the alterations of the ovarian blood flow under physiologic and pathophysiologic conditions.