Oocyte in vitro maturation (IVM) is an assisted reproductive technology in which immature oocytes are retrieved from antral follicles. It has been applied mainly in patients with an increased risk of ovarian hyperstimulation syndrome, particularly in patients with polycystic ovarian syndrome. Moreover, it has been proposed as an alternative approach for fertility preservation for oncological patients. We report the first IVM case in Chile, preformed at the Centre for Reproductive Medicine at Clínica Monteblanco, in a patient with suspected ovarian resistance to FSH, who with the consent of her parents, performed IVM to preserve her fertility.