A prospective study of 106 orthopedic patients was performed for the detection of infection in the early postoperative stage using 99mTc-labeled murine Mabs directed against epitopes on granulocytes. Accuracy was 81% in the hips (n = 26), 81% in the thigh (n = 21), 84% in the knee (n = 19), and 100% in the tibia (n = 27). The technique did not work well in the spine where false-negative results were observed in the three patients studied. One patient suffered transient swelling of the eyelids following injection. Optimal imaging results were obtained 2-6 hr postinjection.