Objective Although previous studies have assessed whether depression is a mortality risk factor, few have examined whether antidepressant medications (ADMs) influence mortality risk. Methods We estimated hazards of 1-year all-cause mortality associated with ADMs, with use occurring within 90 days of depression diagnosis among 720 821 patients who received treatment in a Veterans Health Administration facility during fiscal year 2006. We addressed treatment selection biases using conventional Cox regression, propensity-stratified Cox regression (propensity score), and 2 forms of marginal structural models. Models accounted for multiple potential clinical and demographic confounders, and sensitivity analyses compared findings by antidepressant class. Results Antidepressant medication use compared with no use was associated with significantly lower hazards of 1-year mortality risk in Cox (hazard ratio [HR], 0.93; 95% confidence interval [CI], 0.90-0.97) and propensity score estimates (HR, 0.94; 95% CI, 0.91-0.98), whereas marginal structural model-based estimates showed no difference in mortality risk when the exposure was specified as as-treated in every 90-day intervals of the 1-year follow-up (HR, 0.91; 95% CI, 0.66-1.26) but showed increased risk when specified as intent-to-treat (HR, 1.07; 95% CI, 1.02-1.13). Conclusions Among patients treated with ADMs belonging to a single class in the first 90 days, there were no significant differences in 1-year all-cause mortality risks. When accounting for clinical and demographic characteristics and treatment selection bias, ADM use was associated with no excess harm.