Purpose: This study aims to determine whether a low dose of the gonadotropin releasing hormone antagonist, cetrorelix, prevents a premature luteinizing hormone (LH) surge and affects in vitro fertilization (IVF) outcomes compared to the standard dose of 0.25 mg/day. Methods: In this study, 45 IVF/intracytoplasmic sperm injection patients were stimulated with recombinant follicle stimulation hormone from day 2 of the cycle. Cetrorelix was injected daily from day 6 of gonadotropin administration. Twenty-two patients received cetrorelix at a dose of 0.25 mg/day, whereas 23 participants received half dose. Results: The mean consumption of gonadotropins was significantly higher in patients receiving 0.25 mg/day of cetrorelix (2,213 vs. 1,350 U; p = 0.046). The clinical pregnancy rates were similar in both groups (31.8 vs. 47.8 %; p = 0.273). Premature LH surge was detected in 9.1 % of the patients receiving cetrorelix 0.25 mg/day and in 13 % of the patients receiving cetrorelix 0.125 mg/day (p > 0.05). The difference between two groups was not statistically significant (p > 0.05). ConclusIons: Our results suggest that there is no difference between a cetrorelix dose of 0.125 or 0.25 mg/day in preventing premature LH rise during ovarian stimulation for IVF. © 2013 Springer-Verlag Berlin Heidelberg.