In the fish oil trial, 41 patients were randomized to fish oil capsules containing 6 grams of n-3 fatty acids daily and 39 patients were randomized to olive oil placebo capsules for an average duration of 28 months. Each fish oil capsule contained 500 mg of n-3 polyunsaturated fatty acids composed of 240 mg of eicosapentaenoic acid, 160 mg of docosahexaenoic acid, and 100 mg of mainly docosapentaenoic acid. Randomization was stratified by medical or surgical treatment for coronary disease and the ratio of total to HDL cholesterol. The primary outcome variable was change in minimal diameter of coronary artery lesions expressed as a continuous variable. During the initial hospital stay for catheterization, dietary instruction was provided to every patient according to the National Cholesterol Education Program (NCEP) Step 1 guidelines. A seven-day diet record was collected at the randomization visit and every three months during the trial. Every twelve weeks, a research nurse reviewed with the patients side effects, diet, and concomitant medications and performed a pill count. Every 24 weeks, the patients received an interval medical history and physical examination by a physician. A fasting blood sample was obtained for lipid analysis at the 12- and 24-week visits and every 24 weeks thereafter. If the total cholesterol level of any patient increased to 250 mg/dl (6.43 mmol/liter) or greater on two consecutive measurements, intensified dietary instruction was given, followed by drug therapy with cholestyramine or nicotinic acid or both as needed to lower total cholesterol to less than 250 mg/dl. Twenty-one patients did not complete the protocol due to death, refusal to undergo the second cardiac catheterization, development of medical conditions precluding participation, intolerance to the capsules, and a missing initial angiogram.