Abstract Introduction Although several studies have shown a link between environmental noise exposure and risk of acute Myocardial Infarction (MI), only few studies have investigated its association with prognosis after MI. We aimed was to analyze the relationship between residential environmental noise exposure and one-year prognosis after a first MI. Methods This observational, longitudinal study was conducted from data collected by a French observatory (RICO) from 2004 to 2009. The outcome was defined by Major Adverse Cardiovascular Events (MACE). Medical data were collected from patients hospitalized for an acute MI from patients registered in the database between January 1st, 2004, and December 31st, 2008, with the following criteria: first MI, aged 18 years or older, with a valid home address and residing in a French urban unit, and who survived at least 28 days after the acute MI were included in the present study. Environmental noise and air pollutants exposure were considered at the residence of the patients. Noise exposure was quantified for two time periods: daily (LAeq,24h) and at night (Lnight) with an annual average. Two outdoor air pollutants were considered: nitrogen dioxide (NO2) and particulate matter with an aerodynamic diameter ≤ 10 µm (PM10). Air pollution exposure levels within the 30 days preceding a major cardiac event (MACE) were estimated. MACE were defined as cardiac death, re-hospitalisation for heart failure, recurrent MI, emergency revascularization, stroke, angina and or unstable angina Results Among the 864 subjects included, most were male (64%), the median age was at 69 y. Nineteen percent (N = 164) presented a MACE during the one year follow-up, and the most frequent were cardiac death (32%). For each 10 dB(A) increase during Lnight , the hazard ratio (HR) of MACE was 1.25 (95% IC 1.09 to 1.43), independently of air pollutants and other confounding. This effect was modified by age and gender. Conclusion and relevance: Our findings suggest for the first time a strong association between noise exposure, in particular during the night, and prognosis at one year after a first MI. If confirmed by larger prospective studies, our study could help to identify original opportunities for environment-based secondary prevention strategies.