Blood loss associated with uncemented total hip arthroplasty can be considerable, and any simple and safe means of reducing this loss and hence the volume of blood transfused during surgery would be valuable. The authors conducted a randomized trial using Colgen, a nondenatured collagen with hemostatic properties, in 76 patients undergoing uncemented total hip arthroplasty. Thirty-eight patients had Colgen sprinkled around the reduced hip joint after arthroplasty and 38 patients acted as controls. Analysis, using Student's t-test, showed no difference between the groups in measured blood loss at operation. However, after surgery in the Colgen group both visible measured blood loss (P less than .05) and total calculated blood loss (P less than .01) were significantly reduced. These results are particularly relevant today, when blood transfusion itself is a potential danger and should be kept to the necessary minimum.