Ovarian hyperstimulation syndrome (OHSS) is a severe complication of ovarian stimulation for assisted reproductive techniques. Clinical manifestations are massive extravascular fluid accumulation and haemoconcentration. Vascular endothelial growth factor (VEGF) has been demonstrated to mediate the development of OHSS. Intravenous albumin at the time of oocyte aspiration has been suggested as an effective prophylactic treatment against the occurrence of severe OHSS. Here it is reported that in cultured human luteinizing granulosa cells, VEGF mRNA expression was enhanced by human albumin and maximum expression was observed in cultured granulosa cells obtained from patients with serum oestradiol concentrations >2000 pg/ml on the day of human chorionic gonadotrophin injection (P < 0. 05).