Introduction: Dietary protein comes from foods with greatly different compositions that may not relate equally with mortality risk. Few cohort studies from non-Western countries have examined the association between various dietary protein sources and cause-specific mortality. Therefore, the associations between dietary protein sources and all-cause, cardiovascular disease, and cancer mortality were evaluated in the Golestan Cohort Study in Iran. Methods: Among 42,403 men and women who completed a dietary questionnaire at baseline, 3,291 deaths were documented during 11 years of follow up (2004-2015). Cox proportional hazards models estimated age-adjusted and multivariate-adjusted hazard ratios (HRs) and 95% CIs for all cause and disease-specific mortality in relation to dietary protein sources. Data were analyzed from 2015 to 2016. Results: Comparing the highest versus the lowest quartile, egg consumption was associated with lower all-cause mortality risk (HR=0.88, 95% CI=0.79, 0.97, ptrend=0.03). In multivariate analysis, the highest versus the lowest quartile of fish consumption was associated with reduced risk of total cancer (HR=0.79, 95% CI=0.64, 0.98, ptrend=0.03) and gastrointestinal cancer (HR=0.75, 95% CI=0.56, 1.00, ptrend=0.02) mortality. The highest versus the lowest quintile of legume consumption was associated with reduced total cancer (HR=0.72, 95% CI=0.58, 0.89, ptrend=0.004), gastrointestinal cancer (HR=0.76, 95% CI=0.58, 1.01, ptrend=0.05), and other cancer (HR=0.66, 95% CI=0.47, 0.93, ptrend=0.04) mortality. Significant associations between total red meat and poultry intake and allcause, cardiovascular disease, or cancer mortality rate were not observed among all participants. Conclusions: These findings support an association of higher fish and legume consumption with lower cancer mortality, and higher egg consumption with lower all-cause mortality. (C) 2016 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.