Thin endometrium in infertile female patients has always been a clinical challenge for the treating reproductive physicians. This study aimed to evaluate the effect of intrauterine instillation of autologous platelet-rich plasma on endometrial thickness and vascularity in infertile female patients with thin endometrium undergoing ovarian stimulation with intrauterine insemination. This prospective randomized control study included 120 women undergoing ovarian stimulation with intrauterine insemination, aged between 21 and 37 years, with persistent thin endometrium (<7 mm) on ≥1 cycle in previous ovarian stimulation cycles, even after conventional treatment with estradiol valerate. The women were randomly assigned to study group A and control group B. Baseline endometrial thickness and endometrial vascularity were noted. Intrauterine instillation of autologous platelet-rich plasma was done on the day of trigger in group A, whereas estradiol valerate was given in group B. Another evaluation of endometrial parameters was done on the day of intrauterine insemination. The cycle was repeated for 3 cycles or until the pregnancy was achieved, whichever occurred earlier. Parameters were noted for both groups. Primary outcomes were the change in endometrial thickness and endometrial vascularity. Secondary outcomes were positive pregnancy rate and clinical pregnancy rate. In group A, mean pre-platelet-rich plasma endometrial thickness was 4.66±0.79 mm, which significantly increased to 7.47±0.85 mm after platelet-rich plasma instillation (P<.05) after 3 cycles. This increase was significantly greater than that observed in group B. There was significant increase in endometrial vascularity in group A compared with group B (P<.05). The positive pregnancy rate and clinical pregnancy rate in group A were 23.73% and 18.64%, respectively, and significantly higher than those in group B. Autologous platelet-rich plasma is a promising, easily procurable, and novel option for management of infertile females with thin endometrium not responding to conventional treatment. Using it in intrauterine insemination cycles can reduce costs and psychological burden of this subgroup of women by reducing the need for resorting to advanced options such as in vitro fertilization and surrogacy.