Abstract: This study analysed the use of re-infusion drains on 99 consecutive patients undergoing total knee arthroplasty surgery at a large hospital. The primary aim was to ascertain the cost effectiveness of the drains. Secondary aims were to assess safety of the drains, whether or not they reduced the need for allogeneic blood transfusion and whether they decreased the length of stay in hospital. As a control group the records of 99 patients treated without re-infusion were analysed retrospectively. The direct cost of consumables increased for the evaluation period. There was a smaller proportion of allogeneic blood transfusion (27% vs 38%) and a smaller mean number of units transfused (0.92 vs 0.54) in the re-infusion group compared to the control group. Patients benefited directly in that the mean length of stay was also significantly shorter in the re-infusion group. The researchers anticipate more direct cost saving with experience and best practice and conclude that the use of re-infusion drains is a cost effective blood saving method in total knee joint arthroplasty.