Background: Links between urban air pollution, mortality, and hospitalizations due to cardiovascular disease have frequently been established. This study specifically examines the short-term associations between pollution and myocardial infarction using data from a registry of ischemic diseases. Methods: The daily number of heart attacks in the Urban Community of Strasbourg was extracted from the Monica registry (Bas-Rhin) for the period 1984–1989. Pollution indicators include the daily average and hourly maximum levels of carbon monoxide (CO), sulfur dioxide (SO2), particulate matter (PM13), nitrogen monoxide (NO), and nitrogen dioxide (NO2), as well as the 10-hour average and maximum levels to 6 p.m. for ozone (O3). The analysis is based on a Poisson regression that accounts for the trend, seasonal variations, temperature, humidity, and each of the pollution indicators using nonparametric smoothing functions. The influence of the day of the week and influenza is also taken into account. Results: The hourly maximum of NO is significantly associated with myocardial infarction (5-day lag, square root function): for a change from the first quartile (63 μg/m³) to the third quartile (189 μg/m³), the RR is 1.087 (95% CI: 1.014–1.166). The association is significant in winter with an RR of 1.129 (95% CI: 1.028–1.241) for a change from the first quartile (101 μg/m³) to the third quartile (265 μg/m³). A statistically significant association was found with the hourly maximum of NO₂ in winter with a 5-day lag: the RR, for a variation from the first quartile (59 μg/m³) to the third quartile (107 μg/m³), is 1.095 (95% CI: 1.015–1.181). The shape of the relationship does not differ from linearity. For the average and maximum O3 levels, a significant association was observed but is not robust. For the other pollution indicators, no association was found. Conclusions: The association observed in this study between NO₂ and ischemic disease has been demonstrated in a number of other studies, both for hospitalizations and mortality, but not in all of them. The concentration of this secondary pollutant could serve as a proxy indicator for the concentration of fine particulate matter.