Objective: To determine whether gonadotropin-releasing hormone (GnRH) analog cotreatment with chemotherapy provides better reproductive outcomes for women at risk of premature ovarian failure (POF) as a side-effect of gonadotoxic chemotherapy. Design: Systematic review and meta-analysis. Setting: University-affiliated research centers. Patient(s): None. Intervention(s): Electronic and manual searches (e.g., MEDLINE, EMBASE, CENTRAL) up to January 2010 were performed to identify randomized controlled trials (RCTs) comparing GnRH cotreatment with chemotherapy alone in premenopausal women. Main Outcome Measure(s): Incidence of POF after treatment, incidence of women with resumption of ovulation, POF after an initial normal cycle, normal cycles but abnormal markers of ovarian reserve, spontaneous occurrence of pregnancy after treatment, and time to reestablishment of menstruation; data also extracted to allow for an intention-to-treat analysis. Result(s): Twenty-eight RCTs were identified, but only six met the inclusion criteria. Data were only available for the incidence of women with new onset of POF, resumption of ovulation, and occurrence of pregnancy. The incidence of POF or resumption of ovulation both demonstrated a statistically significant difference in favor of the GnRH cotreatment. The occurrence of spontaneous pregnancy showed no statistically significant difference between GnRH cotreatment and the control groups. Conclusion(s): Evidence from RCTs suggests a potential benefit of GnRH cotreatment with chemotherapy in premenopausal women, with higher rates of spontaneous resumption of menses and ovulation but not improvement in pregnancy rates. Data relating to study quality and possible bias for the majority of the outcomes in this review were not available, denoting possible selective reporting of trial data. ©2011 by American Society for Reproductive Medicine.