The standard goal of all fertility treatments is the improvement of pregnancy rates in infertile patients. Within the last 20 years, ovulation induction has contributed to the success of assisted reproduction techniques e.g. in vitro fertilization (IVF) and embryo-transfer (ET). The efficacy of these techniques depends on a personalized protocol of controlled ovarian hyperstimulation (COH) and adequate oocytes recruitment. The response to common ovarian stimulation protocols is not always as expected. Failure to respond adequately to standard protocols and to recruit adequate follicles is called 'poor response' in these patients although it is highly correlated with age. However, in younger women it might be associated with advanced endometriosis or prior ovarian surgery, gonadotoxic chemotherapy, ovarian radiation, pelvic infection and certain genetic conditions (including mosaic turner syndrome, FMR1 pre-mutation carriers) which are common causes of diminished ovarian reserve (DOR). Several tests have been suggested but none of them has significant value to predict DOR. Furthermore, an accurate diagnostic test of low ovarian reserve would help the clinicians to use the most suitable COH protocol and resulted in declining the cost and psychological decay. However, the ideal stimulation for diminished ovarian reserve still is great challenge for the clinician and patient.