Welcome to the Web site of the Physicians' Health Study. This landmark study was begun in the fall of 1982 to test the benefits and risks of aspirin and beta carotene in the primary prevention of cardiovascular disease and cancer. Twenty-five years and nearly 300 published research reports later, it is still going strong.

The original randomized trial, the Physicians' Health Study-I, ended in 1995. Its finding that daily low-dose aspirin decreased the risk of a first myocardial infarction by 44% helped focus on the role of aspirin in primary prevention of coronary heart disease. It also showed no benefit or harm from beta carotene, a finding that allowed investigators to turn to other, more promising agents. Although that trial may be over, the physicians who took part in it continue to help advance our knowledge about the prevention of cardiovascular disease, cancer, and other chronic diseases by completing annual questionnaires. A second randomized trial, the Physicians' Health Study-II, was started in 1997 to test the balance of benefits and risks of three other widely used, but as yet unproven, supplements for the primary prevention of cardiovascular disease, cancer, and age-related eye disease--vitamin E, vitamin C, and a multivitamin. The vitamin C and vitamin E components ended as planned in late 2007 (data analysis is underway), but the multivitamin component will continue for a few more years. Because the PHS II is the only existing large-scale randomized trial of multivitamins for chronic disease prevention, the results are expected to have a substantial impact on personal and clinical decision making.