Treatment of hypercholesterolemia with HMG-CoA-reductase inhibitors has revolutionized medical intervention towards the prevention of coronary artery disease. There is a wide sprectrum of patients with diverse underlying clinical conditions that may benefit from treatment using these agents. These include patients with multiple risk factors, individuals following major vascular events, and those with special conditions that are associated with accelerated atherosclerosis. The latter include patients with severe, dominantly inherited hypercholesterolemia, patients with major organ dysfunction such as chronic renal failure, and individuals after transplantation. Multimodality intervention includes behavior modification and mechanical as well as pharmacological treatment. It is aimed at several important targets: cholesterol reduction, control of hypertension and diabetes, improvement of myocardial contractility, reduction of infarct size, and control of hemostasis. Most of these patients require multiple drugs, which may interact at the pharmacodynamic (efficacy and safety) as well as pharmacokinetic levels. These potential interactions should be considered while planning and implementing preventive measures for an individual as well as for the community. The beneficial effects and the potential hazardous interactions between HMG-CoA reductase inhibitors and other medications are presented and discussed using two models: heterozygous familial hypercholesterolemia and major organ transplantation. Although there is a partial overlap in the medications used for the treatment of these two conditions, some of them differ. The interaction between HMG-CoA reductase inhibitors and other cholesterol-lowering agents, mainly fibrates, is discussed in the first model summarizing data from controlled clinical trials. The interaction with cyclosporin A is presented using the second model. A potential benefit of fluvastatin, as compared with other currently available HMG-CoA reductase inhibitors, which may be related to its relatively short plasma half-life and low systemic exposure, is discussed.