Analysis of a contemporary cohort of patients on dialysis revealed that mortality from acute myocardial infarction (AMI) has decreased, whereas the prevalence of AMI has increased markedly, particularly among patients with non-ST elevation myocardial infarction (NSTEMI). Using inpatient discharge diagnosis codes (1993–2008), we determined that proportions of AMI claims decreased in the primary position (from 65% to 52%) but increased in the secondary position (from 35% to 48%). Proportions of NSTEMI codes increased remarkably in both the primary and secondary positions. The progressive increase in diagnostic claims for secondary AMI identifies a unique high-risk population and has important clinical, economic, and epidemiologic implications among patients on dialysis.