Purpose The aim was to determine pregnancy rate following intrauterine insemination (IUI) and its associated factors in a university assisted reproductive technique center in Tehran, Iran. Methods A retrospective analysis of 350 IUI cycles with ovarian stimulation by clomiphene citrate and/or gonadotropins was performed. Results The overall pregnancy rate was 22% (77/350). Of the 77 pregnancies, 88.3% resulted in live birth, 7.8% in spontaneous abortion, 2.6% in blighted ovum and 1.3% were ectopic. Logistic regression analysis revealed three predictive variables as regards pregnancy: number of the treatment cycle (OR:3.5 CI:1.9 -6.4 p:0.006), duration of infertility (OR:2.1 CI:1.2 -3.7 p=0.001) and age (OR:2.15 CI:1.1 -4.4 p=0.04). Pregnancy rate did not have any independent relation to sperm count, type of infertility, number and size of follicle and side of ovulatory ovary. Conclusion Our results indicate that clomiphene citrate and/or gonadotropins IUI is a convenient and useful treatment option in women with younger age ( <30 years) and fewer treatment cycles and fewer infertility duration (4 years).