Few studies have evaluated the efficacy of cholesterol-lowering interventions in a community setting and have included a control or comparison group. As part of a preventive health demonstration project in rural Pennsylvania, Medicare beneficiaries underwent cholesterol screening to identify high-risk individuals with serum cholesterol levels > or = 240 mg/dL. These high-risk individuals were randomized to a cholesterol-lowering intervention through either local hospitals or physicians' offices or to a control group. Baseline and follow-up serum cholesterol levels collected two to three years later were compared according to service location (hospital versus physician's office), intervention attendance, degree of participation, baseline heart disease history, and cholesterol-lowering medication use at follow-up. Serum cholesterol levels decreased between 5.7% and 6.6% in the hospital-based and physician-based groups, as well as in a control group not offered the intervention. Participation rates did not differ between treatment groups, nor did participation affect serum cholesterol levels. Attendance level and heart disease history were not associated with a greater decrease in serum cholesterol levels. Individuals reporting cholesterol-lowering drug use at follow-up had significantly higher baseline serum cholesterol levels and a significantly greater decrease in total serum cholesterol (P < .0001) than those not on medication. Both nonpharmacological (diet) and pharmacological (drug) interventions will reduce serum cholesterol levels and heart attack risk. The study results suggest that, at least for older individuals, the impact of nonpharmacological interventions on the community is minimal. We conclude that only very aggressive treatment will significantly loser serum cholesterol levels in older individuals at risk for heart attack.