The Don Army Territory in southern Russia from 1867 to 1916 offers a unique opportunity to follow mortality variations across religious denominations (Orthodox, Old Believers and Coreligionists, Catholics, Lutherans, Jews, Armenian-Gregorians, Buddhists, and Muslims) in a context of severe climatic conditions, urbanization, economic mutations, and improvements in hygiene and medicine. Denominational groups were differentiated by ways of life, residential segmentation, hygiene practices, and medical knowledge. The most educated and urban denominations had the lowest mortality. Religions determined mortality patterns, doing duty for nonexistent or scarce physicians among the Orthodox, laying down rules of hygiene, and promoting doctrine on fertility and child care.