Objective: The purpose of this retrospective study was to compare 2 different methods of luteal phase support in in vitro fertilization patients after embryo transfer. Methods: In 101 embryo transferred cycles 35 of the patients were given hCG supplemental (starting the day before embryo transfer 1500 IU every 3 days for 6 times), 54 of them were given progesterone in oil (50 mg/day, IM injection, 20 days) randomly, except when E2 levels exceeded 3000 pg/ml. We had 9 pregnancies in hCG group, 10 with progesterone group. Results: The comparison of results showed no significant difference between the 2 groups. Of the 9 patients who used hCG 6 aborted, of the 10 pregnant patients in progesterone group, 4 aborted. Conclusion: There was no difference from pregnancy rate point of view, but hCG group had a trend to abort more frequently (Fischer's exact test, p=0.06).