Pre-operative "isovolaemic" haemodilution using 6% hydroxyethyl-starch was used in 7 patients with tumours involving the mouth. While the value of isovolaemic haemodilution in terms of reducing transfusion requirements with donor blood was confirmed, this positive effect was found to be offset by the narrow margin within which blood pressure can be reduced intra-operatively and by the resultant higher blood loss. Wound healing was optimal by clinical evidence. Defective wound healing or necroses due to local hypoxaemia appear to be less likely after isovolaemic haemodilution.