Objective: To estimate the annual number and costs of coronary heart disease (CHD) events in the United States attributable to insulin resistance among individuals with and without type 2 diabetes. Research Design and Methods: Medline-indexed articles and government statistical reports were screened for data on the prevalence of insulin resistance, the relative risk of. CHD by insulin resistance status, and number of CHD events per year among individuals with and without type 2 diabetes. These data were used to estimate the number of CHD events per year by insulin resistance and type 2 diabetes status, the proportion of CHD events attributable to insulin resistance, and the annual cost of these events. Results: Of the 171,000 annual CHD events in the type 2 diabetes population, 164,000 (96%) occurred in those with insulin resistance, 80,000 of which were attributable to insulin resistance. Of the 929,000 annual CHD events in the non-type 2 diabetes population, 162,000 (17%) occurred in patients with insulin resistance, 58,000 of which were attributable to insulin resistance. Thus, insulin resistance is responsible for 46.8%, 6.2%, and 12.5% of the annual CHD events in the type 2 diabetes, non-type 2 diabetes, and total US population, respectively. The estimated annual total cost of these insulin resistance-attributable events was $12.5 billion in the United States in 1999, of which $6.6 billion were direct medical costs. Conclusion: Preventing or modifying insulin resistance may reduce the morbidity, mortality, and costs associated with CHD.