Patients undergoing surgery, especially hip and knee surgery, are at high risk for VTE. The administration of drugs for thromboprophylaxis, such as heparins, significantly lowers that risk, but heparins have to be applied by injections below the skin. The purpose of this study was to compare the safety and efficacy of BAY 59-7939 with the safety and efficacy of the licensed drug enoxaparin and to find the optimal dose of BAY 59-7939 for the anticipated phase III trials. Enoxaparin, a so-called low molecular weight heparin, is approved and widely used in the area of thromboprophylaxis and was given once daily subcutaneously. In this study 5 different doses of the investigational drug BAY 59-7939 were tested in comparison to Enoxaparin. The following doses of BAY 59-7939 were tested: 2.5 mg twice daily (5 mg total daily dose); 5 mg twice daily (10 mg total daily dose), 10 mg twice daily (20 mg total daily dose), 20 mg twice daily (40 mg total daily dose) and 30 mg twice daily ( 60 mg total daily dose). This study ran for approximately 7 months in a number of countries. In total, 726 patients were enrolled in this study.