The authors report the results obtained with antibiotic and antithromboembolic prophylaxis used in 700 consecutive primary total hip arthroplasties. As for antibiotic prophylaxis (5 cases of infection: 0.7%) the various types of antibiotic used always kept the infection rate under 1%, confirming the effectiveness of the preventive use of antibioticotherapy. The incidence of deep venous thrombosis and pulmonary embolia were 3.7% and 0.7%, respectively (26 cases of DVT and 5 of PET). The incidence of DVT rose to 34.4% in a selected group of cases in which phlebography had been carried out even in the absence of symptoms of DVT. This confirms that the routine use of this method would without a doubt be useful in preventing complications with a high risk for the life of the patient (pulmonary embolia). As for pharmacological prophylaxis, indobufene and calcium heparin were the drugs used most: their effectiveness was nearly similar, despite the fact that the use of calcium heparin in patients considered to be at a higher risk for thromboembolic complications should be made clear.