Objective: To evaluate endometrial and subendometrial blood flow parameters, follicular vascularity, assess the relationship between blood flows and pregnancy outcome. Material and method: A prospective study done in tertiary care center. 204 women with infertility undergoing controlled ovarian stimulation and intrauterine insemination were enrolled. Transvaginal ultrasound with the Doppler flows was performed, on the day of hCG trigger. Endometrial blood flow, endometrial morphology, follicular vascularity and pulsatility index of uterine artery was studied. These findings were correlated with the pregnancy outcomes. The primary outcome was clinical pregnancy rate and secondary outcomes were miscarriages and ectopic pregnancy. Results: The maximum clinical pregnancy rate (11.18%) was observed with triple line endometrium and endometrial thickness more than 8 mm on the day of trigger. 11 cases who conceived and continued the pregnancy had endometrial blood flow till Zone 3. 15.59% clinical pregnancy rate when follicular vascularity was between 51% and 75%. The clinical pregnancy in 16 cases (p-value = 0.323) was observed when the pulsitality index of uterine artery was between 2 and 3.2 on the day of trigger. Conclusion: The pregnancy outcome is poor if the endometrial flows are absent, PI of uterine artery is less than 2 or more than 3.2 and follicular vascularity is less than 50% on the day of trigger. The endometrial blood flow Doppler studies and follicular vascularity on the day of trigger in COS cycles with intrauterine insemination can be useful in predicating pregnancy outcomes. Interventions can be planned in COS cycles to improve pregnancy outcomes.