Vancomycin can cause two types of hypersensitivity reactions, the red man syndrome and anaphylaxis. Red man syndrome has often been associated with rapid infusion of the first dose of the drug. The aim of this study was to investigate the haemodynamic changes that follow the appearance of pruritus during vancomycin administration and development of red man syndrome. We studied 50 patients scheduled for coronary artery bypass surgery, and we compared data from patients who exhibited pruritus with those from patients who did not. Before induction of anaesthesia, vancomycin (15 mg/kg) was continuously infused at a constant rate over 30 min. Haemodynamic profiles were recorded before; during and after the beginning of vancomycin infusion.