Smoking is a risk factor for postoperative complications such as pneumonia, infections and impaired wound healing. These can be reduced by preoperative stop-smoking intervention six to eight weeks before surgery. The aim of this study was to evaluate the costs and benefits of a stop-smoking intervention program by means of cost consequence analysis (CCA). A total of 120 smokers scheduled for hip or knee alloplasty were randomised to either a control group or an intervention group. The intervention group received an intensive stop-smoking intervention six to eight weeks before surgery. The focus of the economic analysis was on direct costs. Diagnosis-related group (DRG) costs were used for estimating the costs of secondary surgery. In all, 64% of the patients in the intervention group stopped smoking before surgery, as opposed to 8% in the control group. In the intervention group, 5.4% of the patients had wound complications, and 3.6% needed secondary surgery. In the control group, 30.8% had wound complications and 15.4% needed secondary surgery. The direct costs were almost the same in the two groups, whereas the overall costs in the intervention group were lower than in the control group. The economic analysis shows that a preoperative smoking intervention program is beneficial to society and the patient alike. Based on these calculations, we recommend that all patients scheduled for hip or knee alloplasty be given preoperative stop-smoking intervention.