Introduction: Health promotion and disease prevention have been increasingly recognized as activities within the scope of emergency medicine. Exercise prescription by physicians has been shown to improve outcomes in obesity, cardiovascular disease, and many other diseases. An estimated 600,000 Canadians receive the majority of their care from emergency departments (ED), representing a substantial opportunity for health promotion. Our study examined the frequency of exercise prescription by emergency physicians (EPs) and determined factors that influence decisions to prescribe exercise. Methods: A national, confidential 22-item survey was distributed to Canadian EPs via email by the CAEP survey distribution protocol in November/December 2015. Demographics, exercise prescription rates and self-reported exercise habits were collected. Results: A total of 332 EPs responded. 92.4% of EPs reported being at least moderately active. 62.7% of EPs often or always council their patients about preventative medicine (smoking cessation, drug and alcohol use, diet and safe sex). However, only 23.8% often or always ask about their exercise habits. Even fewer (12.7%) often or always prescribe exercise. Training background significantly predicted level of comfort prescribing exercise. CCFP trained EPs were 5.1 (p = 0.001) times more likely than trained EPs to respond 'yes' they feel comfortable prescribing exercise, and 3.7 (p = .009) times more likely to respond 'sometimes'. CCFP (EM) trained EPs were 3.5 (p < 0.001) times more likely than trained EPs to respond 'yes' they feel comfortable prescribing exercise, and 2.0 (p = .031) times more likely to respond 'sometimes'. 76.1% of respondents believe that other EPs rarely or never prescribe exercise. Of respondents, only 36% feel comfortable prescribing exercise. The majority of EPs (73.4%) believe that the ED environment did not allow adequate time for exercise prescription. Conclusion: The majority of EPs council their patients regarding other forms of preventative medicine but few prescribe exercise to their patients. Available time in the ED was cited as a significant barrier to exercise prescription. CCFP trained EPs are more comfortable prescribing exercise, suggesting that their training may better educate and prepare them to council patients on exercise compared to trained EPs. Further education may be required to standardize an approach to prescribing exercise in the ED.