OBJECTIVES: This investigation was undertaken to study the costs of a Case Method Learning (CML)-supported lipid-lowering strategy in secondary prevention of coronary artery disease (CAD) in primary care. METHODS: This prospective randomized controlled trial in primary care with an additional external specialist control group in Södertälje, Stockholm County, Sweden, included 255 consecutive patients with CAD. Guidelines were mailed to all general practitioners (GPs; n=54) and presented at a common lecture. GPs who were randomized to the intervention group participated in recurrent CML dialogues at their primary health-care centers during a 2-year period. A locally well-known cardiologist served as a facilitator. Assessment of low-density lipoprotein (LDL) cholesterol was performed at baseline and after 2 years. Analysis according to intention-to-treat-intervention and control groups (n=88)--was based on group affiliation at baseline. The marginal cost of lipid lowering comprised increased cost of lipid-lowering drugs in the intervention group compared with the primary care control group, cost of attendance of the GP's in the intervention group, and cost of time for preparation, travel, and seminars of the facilitator. Costs are as of 2002 with an exchange rate 1 U.S. dollar = 9.5 SEK (Swedish Crowns). RESULTS: Patients in the primary care intervention group had their LDL cholesterol reduced by 0.5 (confidence interval [CI], 0.1-0.9) mmol/L compared with the primary care control group (p