In alloarthroplasty of the hip joint due to coxarthrosis a randomized prospective controlled study was performed to test the efficiency of prophylactic antibiotics in reducing the postoperative infection rate. The minimum follow-up time was 730 days. There were three infections (two superficial and one deep) in the group who received antibiotics (105 patients), 10 infections (two superficial and eight deep) in the control group (89 patients). The overall rates of infections and also the rate of the deep wound infections were significantly lower in patients who received prophylactic antibiotics.