Little is known about trends in the age of onset of first myocardial infarction. Thus, we examined trends in the age of onset distribution of first myocardial infarction using two population-based datasets from Germany. First, we used German claims data based on an annual case number of approximately 2 million women and men covering the period from 2006 to 2016. Second, we used data from the KORA (Cooperative Health Research in the Region of Augsburg) Myocardial Infarction Registry covering the period from 2000-2016. Analyses were performed by means of quantile regression to estimate trends across the whole distribution of age of onset. Overall, N-Sample 1=69627 and N-Sample 2=9954 first myocardial infarctions were observed. In both samples, we found highly heterogeneous trends in age of onset. In men, we consistently found that age of onset increased before 50 and after 70 but decreased within this age bracket. For women, on the other hand, we consistently found that age of onset decreased for first myocardial infarctions before 70 but increased slightly or remained relatively stable thereafter. Therefore, late myocardial infarctions tended to occur later in life, while regular myocardial infarctions tended to occur earlier. These results suggest that in myocardial infarction, both morbidity compression and morbidity expansion might have occurred at the same time but for different parts of the age at onset distribution.