Low response of patients with diminished ovarian reserve to exogenous gonadotropins in controlled ovarian stimulation (COS) protocols is one of the important problems of reproductive endocrinology. Various treatment protocols have been developed in patients with diminished ovarian reserve (DOR) or poor ovarian response (POR). Recently, the addition of growth hormone (GH) to treatment protocols has been brought to the agenda in these patients. In this study, we aimed to investigate the effect of GH adjuvant treatment on intracytoplasmic sperm injection (ICSI) cycle results in patients with DOR or POR. This retrospective cohort study was carried out with patients who diagnosed as DOR or POR and underwent ICSI. The patients were divided into the groups according to whether GH was used. In this study, ongoing pregnancy rates and live birth rates were observed to be significantly higher in the group receiving GH compared to the control group. In addition, there was a significant increase in embryo quality in the group receiving GH. As a result, the addition of GH to COS protocols in DOR and POR patients may increase the ongoing pregnancy rate, live birth rate, embryo quality.