Background: Controlled ovarian stimulation (COS) has contributed to improving the pregnancy rate of women who undergo in vitro fertilization (IVF) by increasing the number of developing follicles and oocytes. Poor ovarian response to controlled ovarian stimulation (COS) remains a major problem in assisted reproduction. Objective: To investigate the effectiveness of treatment with transdermal testosterone gel (TTG) before controlled ovarian stimulation (COS) in low responders undergoing intracytoplasmic sperm injection (ICSI). Patients and Methods: A total of 300 patients who were defined as poor responders using BOLOGNA criteria were randomized into TTG pretreatment group and control group. For TTG pretreatment group, 10 g of TTG (5 % testosterone) for 15–20 days with a 5 mg/d nominal delivery rate of testosterone were applied daily for 15-20 days in the cycle preceding COS for IVF. Main Outcome Measure(s): COS results and IVF outcome. Result(s): There were no differences in patients' characteristics between the two groups. Total dose and days of human menopausal gonadotrophins (HMG) used were significantly lower in the TTG pretreatment group than in the control group. The numbers of oocytes retrieved, mature oocytes, fertilized oocytes, and good-quality embryos were similar in both groups. Embryo implantation rate, clinical pregnancy rate per cycle and live birth rate did not show any statistically significant difference between the two groups. Conclusion: Transdermal testosterone pretreatment did not significantly increase the number of retrieved oocytes, clinical pregnancy rate or live birth rate in poor responders undergoing ICSI trials, however it reduces the total dose and number of days of HMG administration.