Previous experiences in subjects with other forms of third space fluid accumulation have shown that albumin is efficacious in preventing and correcting haemodynamic instability. Using a similar approach in an effort to increase the serum oncotic pressure and to reverse the leakage of fluids from the intravascular space, high risk subjects for severe ovarian hyperstimulation syndrome (SOHS) were treated with albumin. In a recent large study two high risk factors were identified, i.e. the number of oocytes and levels of serum oestradiol. Thirty-six women undergoing assisted reproductive techniques who presented both these factors, received intravenous albumin at a dose of 5% in Ringers lactate in doses of 500 ml during oocyte retrieval and 500 ml immediately thereafter in the recovery room. Daily measurements of urine output, serum and urine electrolytes, weight, abdominal girth, and haematocrit prior to and after oocyte retrieval revealed normal serum and urine electrolyte levels, and no signs of haemoconcentration. No patient in this study developed SOHS, and of course none had to be hospitalized. Vaginal ultrasound performed in the majority of the subjects revealed < or = 100 ml of peritoneal fluid 48-72 h after oocyte retrieval. The only complication from the use of intravenous albumin was the appearance of a 'flu-like condition' (low grade temperature, nausea and muscle pains) developed by 12 women between days 3 and 5 after oocyte collection. Intravenous albumin had thus prevented the development of severe ovarian hyperstimulation syndrome in an assisted reproduction programme.(ABSTRACT TRUNCATED AT 250 WORDS)