OBJECTIVE To report our experience with i.v. albumin as a means to prevent ovarian hyperstimulation syndrome (OHSS) in high-risk patients. DESIGN Retrospective case-series. SETTING University hospital-based IVF program. PATIENTS Five women undergoing controlled ovarian stimulation for IVF-Based on previous history and/or E2 measurements and number of ovarian follicles, these patients were considered to be at high risk for developing OHSS. INTERVENTIONS Intravenous albumin was given at the time of oocyte retrieval. Additional doses were given 12 and 24 hours later. MAIN OUTCOME MEASURE Development of OHSS. RESULTS Four patients developed OHSS; two of them had the severe form of the syndrome. CONCLUSIONS Severe OHSS may develop in high-risk patients despite the prophylactic administration of i.v. albumin.