Objective To evaluate the safety and efficacy of microporous polysaccharide hemi-spheres (MPH) in controlling blood loss in total knee arthroplasty (TKA). Methods A total of 80 pa-tients with osteoarthritis who would undergo unilateral TKA were randomized prospectively into 2 equal groups. In trial group, during TKA, MPH was sprayed into the capsule and on the muscle and tendons to control bleeding. In control group, patients did not receive MPH. The blood loss (overt and occult), postoperative decrease in hemoglobin, volume of blood transfusion, time for active straight-leg raising, time for 90-degree knee flexion, range of active motion, deep vein thrombosis (DVT) and incision complications were recorded and compared between the 2 groups. Results The overt and occult blood loss and postoperative decrease in hemoglobin were lower in the trial group than in the control group. The trial group required less blood transfusion than the control group. In the range of active motion on the 7th, 15th and 19th days postoperatively, the trial group was better. In the trial group, 2 patients had wound effusion and 6 had DVT; in the control group, 2 pa-tients had wound effusion and 7 had DVT. The differences were insignificant. Conclusion Intraoperative MPH usage is safe and effective in controlling intra- and postoperative bleeding.