Changes in intraovarian arterial blood flow were monitored by means of colour-coded and pulsed Doppler ultrasonography in Beagle bitches during the normal oestrous cycle (n = 11) and pregnancy (n = 3), and at PGF(2alpha)-induced luteolysis (n = 4). The ultrasonographic findings were related to the reproductive stage of the bitch, as determined by vaginoscopical and cytological criteria, and by the concentrations of oestradiol, LH and progesterone in peripheral blood plasma. Colour-coded Doppler ultrasonography was used to visualize and estimate intraovarian vascularization, and pulsed Doppler ultrasonography was used to measure the arterial blood flow. The systolic and diastolic peak velocities, the end-diastolic velocity, and the pulsatility index and resistance index were calculated for quantitative analysis of the Doppler waveforms. Intraovarian perfusion increased gradually during pro-oestrus. A marked enhancement of intraovarian colouring and blood flow velocities, and a decline in the indices for pulsatility and resistance were observed in the preovulatory period. Maximum perfusion was observed at ovulation and during the early luteal phase. Significant differences (P < 0.05) were detected for the values of all calculated Doppler parameters 2 days before and 2 days after ovulation. Intraovarian blood flow decreased gradually in accordance with luteal regression. Treatment with PGF(2alpha) caused a distinct decline in luteal activity and a concomitant reduction in intraovarian perfusion. The values of blood flow parameters found during the luteal phase of pregnant bitches were comparable to those of the normocyclic bitches. Doppler ultrasonography of the intraovarian arteries in bitches provides complementary information about cyclic changes of ovarian function.