High blood pressure affects nearly one in three individuals in the United States. There are many factors that can cause high blood pressure, including family history and genetic traits, kidney disease, stress, diabetes, and diet. If left untreated, high blood pressure can increase one's risk for stroke, heart attack, and heart failure. There are four major classes of drugs used to treat high blood pressure, which include diuretics, beta blockers, angiotensin converting enzyme (ACE) inhibitors, and calcium antagonists. Each class works differently in treating high blood pressure, and certain gene regions may affect the effectiveness of the various high blood pressure drugs. The purpose of this study is to identify new gene regions that may influence the effectiveness of the four major high blood pressure drug types in preventing a heart attack, sudden death, or stroke.