Objective: The American Heart Association has endorsed depression as a cardiac risk factor and recommends screening as part of routine practice. This has been met with controversy due to inconsistencies in the data linking depression treatment to better cardiovascular outcomes. Our objective was to prospectively assess the association between depression treatment (defined as being prescribed antidepressant medication) and major adverse cardiovascular events (MACE) in patients referred for exercise stress tests. Method: Two thousand three hundred eighty-five consecutive patients presenting for myocardial perfusion exercise stress tests underwent a sociodemographic, medical, and psychiatric interview (Primary Care Evaluation of Mental Disorders [PRIME-MD]) and completed the Beck Depression Inventory (BDI). History of cardiovascular disease (CVD) and antidepressant use was self-reported and verified via chart review. Participants followed over an 8.8-year follow up, and information regarding MACE incidence (including cardiac mortality, nonfatal myocardial infarction, revascularization procedures, cerebrovascular events) was obtained from provincial administrative databases. Results: 8% (n = 190) of the sample were taking antidepressants at baseline, 41% (n = 916) had a history of CVD, and 38.7% (n = 921) had depression according to the PRIME-MD or BDI. Antidepressant treatment was associated with a 30% reduced risk of MACE (Hazard ratio [HR] = 0.697; 95% confidence interval [CI] = [0.504, 0.964]; p = .029). A 46% reduction in risk was associated with antidepressant treatment among those without CVD (HR = 0.542; 95% CI [0.299, 0.981]; p = .043). In depressed patients, a 33% reduction in risk of MACE associated with antidepressant use was seen (adjusted HR = 0.674; 95% CI [0.440, 1.033]; p = .07). Conclusions: Antidepressants may be cardio-protective among patients presenting for stress testing independent of risk factors including CVD and depression. Results support treating depression with antidepressants in this population to reduce risk of MACE.