The purpose of this study was to review the rationale for vaginal progesterone treatment as luteal support in IVF, and the clinical experience with vaginal micronized progesterone gel. It was found that luteal support with exogenous progesterone significantly improves implantation and pregnancy rates after IVF. Vaginal administration offers a number of potential advantages over intramuscular injection in terms of tolerability and convenience. The clinical experience with Crinone 8%, a vaginal gel containing 90 mg micronized progesterone in a polycarbophil base, indicates that the use of this preparation is associated with pregnancy rates comparable with those achieved after intramuscular administration of progesterone. Moreover, in studies in which patient preferences have been assessed, significantly higher preferences for vaginal micronized progesterone gel have been reported, compared with intramuscular administration or vaginal suppositories. In conclusion, the vaginal micronized progesterone gel used in this study provided effective and well-tolerated luteal support in women undergoing IVF.