Objective: To compare the clinical outcomes between oral micronized progesterone and dydrogesterone as a luteal phase support in stimulated intrauterine insemination (IUI) cycles. Methods: A retrospective analysis was performed in 183 IUI cycles during January 2007 to August 2009. Superovulation was achieved by using gonadotropins combined with or without clomiphene citrate. The luteal phase was supported by oral micronized progesterone 300 mg/day (n=136 cycles) or dydrogesterone 20 mg/day (n=47 cycles) from day of insemination. Results: There were no significant differences in clinical characteristics such as age of female, infertility factors, number of mature follicles ($geq$16 mm), total motile sperm counts, and endometrial thickness on triggering day between the two groups. The clinical pregnancy rates per cycle were similar between the two groups (21.3% in the micronized progesterone group vs. 19.1% in the dydrogesterone group, p=0.92). The clinical miscarriage rate tended to be 3-fold higher in the micronized progesterone group (34.5% vs. 11.1%, p=0.36). Conclusion: Supplementation of oral dydrogesterone as a luteal support has similar clinical outcomes compared with oral micronized progesterone. Large-scaled randomized study would be required to confirm our findings.