Objective: The aim of this study was to compare the outcomes of in vitro fertilization (IVF) in patients with a poor ovarian response who used methyltestosterone, versus those using a placebo, in an infertility clinic setting. Methods: This clinical trial included 120 women who had undergone IVF with intracytoplasmic sperm injection due to poor ovarian reserve and infertility. The study took place at the Yas Infertility Center in Tehran, Iran, between January 1, 2018 and January 1, 2019. In the intervention group, 25 mg of methyltestosterone was administered daily for 2 months prior to the initiation of assisted reproductive treatment. The control group was given placebo tablets for the same duration before starting their cycle. Each group was randomly assigned 60 patients. All analyses were performed using SPSS ver. 23 (IBM Corp.). Results: The endometrial thickness in the intervention group was 7.57±1.22 mm, whereas in the control group, it was 7.11±1.02 (p=0.028). The gonadotropin number was significantly higher in the control group (64.7±13.48 vs. 57.9±9.25, p=0.001). However, there was no significant difference between the two groups in the antral follicular count. The chemical and clinical pregnancy rates in the intervention group were 18.33% and 15% respectively, compared to 8.33% and 6.67% in the control group. The rate of definitive pregnancy was marginally higher in the intervention group (13.3% vs. 3.3%, p=0.05). Conclusion The findings of this study suggest that pretreatment with methyltestosterone significantly increases endometrium thickness and is associated with an increase in the definitive pregnancy rate.