Type 2 receptors for vascular endothelial growth factor are believed to be involved in the pathophysiology of ovarian hyperstimulation syndrome (OHSS). The objective of this study was to examine the preventive effects of cabergoline on OHSS and its complications. The study is a non randomized clinical trial conducted in 2006-2008 on 75 patients, which were at risk of OHSS and underwent assisted reproductive techniques. The diagnosis and severity of OHSS were determined using standard criteria. The study included an intervention and a control group. The intervention group comprised of 50 women at risk of OHSS, who were treated with cabergoline (1 mg every other day for 8 days) commencing from the day of ovum pick up. The control group comprised of 25 historical cases, which were similar to the case group. The latter group did not receive cabergoline, and their OHSS, if occurred, were managed conservatively after hospital admission. The rates of OHSS, baseline characteristics, ovarian stimulation parameters, and pregnancy occurrence were compared. There was no significant difference be-tween baseline characteristics or ovarian stimulation parameters form the two groups. The incidence of OHSS in the cabergoline-treated group, was significantly (P=0.01) lower than that in the control group (12% vs 36%). Embryo freezing was significantly (P=0.001) lower in the control group, but cycle cancellation was significantly (0.03) lower in the cabergoline group. The findings of the study indicate that cabergoline reduces the incidence of OHSS, and is not associated with adverse effects on pregnancy.