In a case-control study a nutritional intervention consisting of an educational program based on the Therapeutic Lifestyle Change diet (TLC) guidelines was implemented in one area of Tehran. Data were collected from subjects in the intervention area (n =133) and controls from another area (n = 183), before and 3.8 years after the intervention. Mean energy and macronutrient intakes and prevalence of risk factors including metabolic syndrome were compared between and within cases and controls. Baseline and follow-up evaluations showed improvement in hypercholesterolemia and high LDL cholesterol levels in cases versus controls. Central obesity and low HDL cholesterol levels increased significantly in controls but not in cases. As there were no significant differences between the 2 groups in energy and macronutrient intakes, it is difficult to claim that nutritional interventions played an important role.