The benefits of blood pressure lowering, lipid lowering, and glycemic control on morbidity and mortality have been established in major long-term clinical trials. The most extensive information is available for diuretics or beta-blockers in hypertension, hepatic hydroxymethyl glutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) in dyslipidemia, and insulin or sulfonylureas in diabetes. Other drug classes provide similar improvements in blood pressure, lipid profile, and glycemic control, and thereby might be expected to provide comparable long-term benefits. As a result, national guidelines advocate treating patients aggressively in order to achieve control of blood pressure low-density lipoprotein (LDL) cholesterol, and blood glucose. The risks associated with drug treatment are generally class-specific. Among antidiabetic agents, sulfonylureas and insulin are associated with risk for severe hypoglycemia, metformin with risk for lactic acidosis, and troglitazone with risk for idiosyncratic hepatocellular injury. Similarly, widely used antihypertensive and lipid-lowering agents are associated with risk for serious complications, such as angioedema with angiotensin-converting enzyme inhibitors, possible increased risk for myocardial infarction and cancer with calcium antagonists, and myositis and liver dysfunction with statins. Physicians must take an aggressive approach to patient management in order to achieve a level of disease control that optimally reduces risk for morbidity and mortality. Serious adverse events may occur rarely with most drug classes; these events can be minimized by appropriately monitoring or selecting patients for treatment.