This chapter describes the role of adjuvants in ovarian stimulation. Objective in assisted reproductive technique (ART) is to use gonadotropins [follicle-stimulating hormone (FSH), luteinizing hormone (LH), human menopausal gonadotropin (hMG)] to obtain optimal number of oocytes and thereby achieve good pregnancy rates. Besides gonadotropins, gonadotropin-releasing hormone (GnRH) analogs usage to prevent an unwarranted premature LH surge has become the standard of practice. Adjuvants in ART have been advocated either to optimize ovarian response during ovarian stimulation or to increase embryo implantation during postimplantation period. Glucocorticoids and aspirin are the most commonly used adjuvants in ART. For the poor responder, numerous adjuvants such as dehydroepiandrosterone (DHEA), letrozole, testosterone, growth hormone, L–arginine, pyridostigmine, etc. have been tried in order to increase the ovarian response. Metformin has been used in high responders to lessen the chances of hyperstimulation and ovarian hyperstimulation syndrome (OHSS).