Transvaginal color Doppler of luteal flow was performed on 58 patients with normal early pregnancy before artificial abortion, 73 patients with proven ectopic pregnancy and 75 non-gravid patients in luteal part of menstrual cycle. The equipment used were Aloka Color Doppler SSD-350 and SSD-680 with a 5 MHz transvaginal probe. Obtained color flow from ovarian tissue was explored with pulsed Doppler and the Pourcelot resistance index was calculated. Typical luteal low-impedance flow was detected in 82.8% cases of early pregnancy, 80.8% cases of ectopic pregnancy and 69.3% cases of non-pregnant women. The lowest resistance index (RI = 0.42 +/- 9.12) of luteal flow was found in cases of non-pregnant women, and the highest resistance index (RI = 0.53 +/- 0.09) was obtained in cases of early normotopic pregnancy. RI in cases of ectopic pregnancy was 0.48 +/- 0.07. Statistical analysis has shown significantly different RI in each of 3 groups of patients (P greater than 0.001). Corpus luteum was seen as early as a few days after ovulation in non-pregnant women and was present until about the 11th week of amenorrhea in pregnant women. In 86.4% patients with proven ectopic pregnancy, luteal flow was detected on the same side as the ectopic pregnancy. Our results have shown different RI value of corpus luteum flow in different groups of patients. Such findings could help to exclude pregnancy, specially with non-specific B-mode ultrasound features. Corpus luteum flow could be used as a guide for searching for ectopic pregnancy.