To determine the effect of local endometrial injury on implantation success in patients diagnosed with unexplained infertility and undergoing intrauterine insemination (IUI) after ovulation induction with gonadotropins. In this prospective randomized controlled trial, 82 infertile patients underwent IUI following ovulation induction with gonadotropin. In the study group (n:40), local endometrial injury (stratch) was performed to the posterior side of the endometrial cavity with a biopsy catheter between the 21-26th days of luteal phase of the cycle preceding ovarian stimulation. There was no statistically significant difference between the study and the control groups in terms of age of female, age of male, duration of infertility, BMI, serum FSH and LH levels, mean dose of gonadotropin and mean duration of ovulation induction (p>0.05). Clinical pregnancy was achieved in two patients (4.76%) in control group and four (10%) patients in the study group, with no significant difference between groups (p=0.18). All pregnancies achieved in the control and the study groups passed 12th gestational weeks and continued. Ectopic pregnancy, multiple pregnancy and abortion was not observed in any patient in both groups. In the study group, pain level immediately after endometrial biopsy procedure was evaluated with visual analog scale (VAS) and it was established that only one (2.5%) patient experienced severe pain after the procedure. Although local endometrial damage in the menstural period before ovulation induction and IUI cycle increases clinical pregnancy rates in the infertile patients, this increase is not statistically significant. Multi-center randomized controlled studies are needed for local endometrial damage to be recommended routinely in clinical practice.