The analysis of the descriptive data from the present trial leads to the following conclusions. A statistically detectable influence of the risk factors for advanced age (for Fraxiparin) are body weight above 80 kg (for calcium heparin), and malignant disease on the development of postoperative DVT was observed. In general, some influence of these risk factors persisted even though prophylactic medication was administered. The statistical considerations on risk factors do not permit any predictions for the individual patient concerning the possible risk of developing DVT. The levels of transaminases and gamma-GT increased by 20 to 30% in both groups during the treatment period. The occurrence of wound hematoma in patients operated on for hernia compared with patients with other surgical interventions revealed a clear dependence of this parameter on the type of operation performed. In keeping with other tolerance data no differences between either treatment was observed concerning the rate of wound hematoma in patients undergoing herniotomy. As to the frequency of DVT, a considerable difference between men and women was recorded in the Fraxiparin group. However, this observation needs to be confirmed in further trials. No difference was detected concerning the onset of DVT in either treatment group: 70% of the thromboses occurred within 3 days after surgery. Significantly, fewer thromboses with clinical signs and fewer proximal vein thromboses occurred in the Fraxiparin group. This seems to be most important for the clinician, since it indicates a twofold effect of the LMW heparin Fraxiparin: Both the frequency of postoperative DVT and the severity of these complications were significantly reduced.