Aims: To demonstrate that tranexamic acid reduces the blood loss incurred as a result of lower limb arthroplasty. Methods: We prospectively studied 30 primary hip and knee arthroplasty patients. Entry criteria were primary joint replacement, exclusion criteria were: a history of bleeding disorders, previous thromboembolic disease or renal insufþciency. The senior author (GS) performed all the operations. Surgical technique and postoperative mobilisation was standardised for both hip and knee arthroplasty cohorts. Tranexamic acid was administered at the time of surgery. The patients had haemoglobin levels assessed preoperatively and a haemoglobin level three days post operatively to allow its stabilisation following surgery. Any blood transfused was noted. Blood was transfused on a case-by-case basis the indications were a haemoglobin less than 8 g/dl or symptoms of anaemia. The results were then compared with a matched population from the bone and joint research unit database. Results: The mean fall in haemoglobin in hip arthroplasty with tranexamic acid was 2.8 ± 0.33 g/dl (95% Conþdence Interval) and 3.85 ± 0.44 g/dl (95% Conþdence Interval) without tranexamic acid this was statistically signiþcant p< 0.05. The mean fall in haemoglobin in knee arthroplasty with tranexamic acid was 1.67± 0.36 g/dl (95% Conþdence Interval) and 2.84 ± 0.35 g/dl (95% Conþdence Interval) without tranexamic acid this was statistically signiþcant p< 0.05. Transfusion requirements were reduced. Conclusions: Tranexamic acid is an inexpensive and effective way of reducing blood loss following hip and knee arthroplasty.