To investigate the effects of dehydroepiandrosterone (DHEA) on FSH and estradiol levels, as markers of ovarian reserve. A total of 32 DOR and/or POF patients received DHEA. We measured hormone profiles of FSH, LH, estradiol, before and after the DHEA treatment. Patients with pre-treatment FSH levels between 15-29 mIU/mL were classified as group 1, patients with FSH levels between 30-49 mIU/mL were defined as group 2, and patients with FSH levels above 50 mIU/mL were categorized as group 3. The mean FSH values decreased when the pooled patients’ results were analyzed (58.5±6.3 vs. 31.5±4.9, P<0.01), but this reduction was most impressive in group 3 patients, who exhibited pre-treatment FSH values above 50 μIU/mL (93.4±10.7 vs. 38.9±7.7, P<0.01). In all patients who used DHEA, FSH levels decreased; however, the decrease was more impressive when patients' FSH levels were initially >50 μIU/mL. Further studies are necessary to provide possible explanations of optimized treatment responses when patients have higher FSH levels.