This study was designed to evaluate the effect of transfusion guidelines on perioperative blood usage with a view to identifying a protocol for transfusion therapy in our hospital. Eighty consecutive patients with normal haemoglobin concentrations presenting for total hip arthroplasty were studied. The maximum allowable blood loss (MABL) was calculated for each patient using the formula of Kallos et al. Blood loss up to this value was replaced with Haemaccel. When the MABL was reached, a haematocrit (Hct) was performed and blood was given if the Hct was less than 30 in men and 27 in women. Otherwise replacement was with Haemaccel. All postoperative complications, duration of hospital stay, and physiotherapy compliance assessments were recorded. A discharge Hct > 36% was the criterion for overtransfusion. The results were compared with findings from a retrospective group before the introduction of these guidelines. Analysis of the data demonstrated a reduction in the frequency of transfusion (97% vs 32% P < 0.05), the volume transfused (2.7 vs 1.3 units P < 0.05), and the incidence of overtransfusion (45% vs 5% P < 0.05) between the two groups of patients. There was no difference between the groups in complication rate, duration of hospital stay or physiotherapy scoring. We conclude that the introduction of guidelines for transfusion in total hip arthroplasty patients has produced a marked reduction in blood usage in our hospital without detrimental effect.