Ovarian arterial velocimetry, using real-time two-dimensional and pulsed Doppler ultrasound, was performed on 36 occasions in nine healthy women with regular menstrual cycles. The change in ovarian arterial compliance was based on the calculation of pulsatility index (PI). In the active ovary carrying a dominant follicle or corpus luteum, the PI in the early follicular phase (mean 6.97, SD 2.01) was significantly higher than that in the late follicular phase (mean 2.36, SD 0.31) (P less than 0.001), and the PI in the early luteal phase (mean 0.68, SD 0.09) was significantly lower than that in the late follicular phase (P less than 0.001). The PI in the late luteal phase (mean 0.93, SD 0.16) was significantly higher than that in the early luteal phase (P less than 0.01). In the inactive ovary, no cyclical changes were seen in the values of PI. There was a significant difference between the values of PI in the active ovary and the inactive ovary in the late follicular, the early and the late luteal phases [2.36 (SD 0.31)] vs [6.29 (SD 1.02)], [0.68 (SD 0.09)] vs [6.18 (SD 1.33)], [0.93 (SD 0.16) vs [6.57 (SD 1.72)] (P less than 0.001), respectively. Use of non-invasive Doppler ultrasound to study physiology of ovarian haemodynamics during the menstrual cycle is of great clinical relevance and paves the way for further investigations on sterility.