Background: The optimal ovarian stimulation dose to obtain the best balance between the probability of pregnancy and the risk of complications, while maximizing cost-effectiveness of in vitro fertilization (IVF) treatment, is yet to be established. Methods: A systematic search of the electronic databases PubMed, EMBASE and Cochrane library, from 1984 until October 2009 for randomized controlled trials comparing different doses of recombinant FSH in IVF, was performed. Results: Ten studies (totaling 1952 IVF cycles) were included in the present meta-analysis, comprising patients younger than 39 years with regular menstrual cycle, normal basal FSH levels and two normal ovaries. Comparison was made between studies using a daily dose of 100 versus 200 IU recFSH, and between 150 versus 200 IU recFSH or higher. Although oocyte yield was greater in the >200 IU/day dose group, pregnancy rates were similar compared with lower dose groups. The risk of insufficient response to ovarian stimulation was greatest in the 100 IU/day dose group. The risk of developing ovarian hyperstimulation syndrome was greater in the >200 IU/day dose group. The number of embryos available for cryopreservation was lowest in the 100 IU/day group, but similar comparing the 150 IU/day and the >200 IU/day dose groups. Conclusions: This meta-analysis suggests that the optimal daily recFSH stimulation dose is 150 IU/day in presumed normal responders younger than 39 years undergoing IVF. Compared with higher doses, this dose is associated with a slightly lower oocyte yield, but similar pregnancy and embryo cryopreservation rates. Furthermore, the wide spread adherence to this optimal dose will allowfor a considerable reduction in IVF costs and complications.