In recent years, value for money in health care has become of increasing concern. There are various ways to perform an economic evaluation, the most simple being a cost-effectiveness analysis, where differences in costs will influence the choice between methods. Cost-utility and cost-benefit analyses represent more advanced forms of economic evaluations. In this cost-effectiveness analysis, the following three strategies aimed at solving the problem of post-operative thromboembolic complications were compared: (a) no prophylaxis but treatment of occurring complications, (b) general prophylaxis with low-dose heparin for patients over 40 years of age and (c) selective treatment based on post-operative surveillance with a fibrinogen uptake test. Moreover, these alternatives were evaluated for three types of surgery: general abdominal surgery, cholecystectomy and elective hip surgery. Costs for thromboembolic and haemorrhagic complications were estimated from data available for patients hospitalized in Malmö. A sensitivity analysis was made with regard to the frequency of thrombosis, prophylactic effect and treatment costs. Health care costs would be minimized with general prophylaxis in hip and general surgery, whereas no prophylaxis is the most cost-effective alternative in cholecystectomy patients, i.e. with a frequency of thrombosis below 8%. General prophylaxis minimized the duration of patients' health losses due to thromboembolic disease in general, as well as in elective hip surgery. After cholecystectomy, no difference in health loss for the individual was found between the alternative of no prophylaxis and general prophylaxis. Selective treatment was always the least satisfactory alternative in all categories and always the most expensive.