Background: Due to improved management, diagnosis, and care of myocardial infarction (MI), patients may now survive long enough to increasingly develop serious noncardiovascular conditions. Objectives: This study aimed to test this hypothesis by investigating the temporal trends in noncardiovascular morbidity and mortality following MI. Methods: We conducted a registry-based nationwide cohort study of all Danish patients with MI during 2000 to 2017. Outcomes were cardiovascular and noncardiovascular mortality, incident cancer, incident renal disease, and severe infectious disease. Results: From 2000 to 2017, 136,293 consecutive patients were identified (63.2% men, median age 69 years). The 1-year risk of cardiovascular mortality between 2000 to 2002 and 2015 to 2017 decreased from 18.4% to 7.6%, whereas noncardiovascular mortality decreased from 5.8% to 5.0%. This corresponded to an increase in the proportion of total 1-year mortality attributed to noncardiovascular causes from 24.1% to 39.5%. Furthermore, increases in 1-year risk of incident cancer (1.9%-2.4%), incident renal disease (1.0%-1.6%), and infectious disease (5.5%-9.1%) were observed (all P trend <0.01). In analyses standardized for changes in patient characteristics, the increased risk of cancer in 2015 to 2017 compared with 2000 to 2002 was no longer significant (standardized risk ratios for cancer: 0.99 [95% CI: 0.91-1.07]; renal disease: 1.28 [95% CI: 1.15-1.41]; infectious disease: 1.28 [95% CI: 1.23-1.34]). Conclusions: Although cardiovascular mortality following MI improved substantially during 2000 to 2017, the risk of noncardiovascular morbidity increased. Moreover, noncardiovascular causes constitute an increasing proportion of post-MI mortality. These findings suggest that further attention on noncardiovascular outcomes is warranted in guidelines and clinical practice and should be considered in the design of future clinical trials.