Background: We examined mortality among working-age Russian men whose identity could not be determined, focusing on where and how they died. Methods: Employing micro-data from deaths that occurred in Izhevsk (Ural region) between June 2004 and September 2005, we analysed the characteristics of decedent men aged 25–54 (n = 2158). Differences between completely identified (n = 1699) and unidentified deaths (n = 282) were compared via logistic regression. Data on all deaths in Russia in 2002 were used for supplemental comparisons. Results: We found that relative to identified men, unidentified men were at a higher risk of death from exposure to natural cold, violence, alcoholic cardiomyopathy, acute respiratory infections and poisonings. Our results also revealed that alcohol played an important role in the mortality of unidentified men. The places and causes of death among these unidentified men provide substantial evidence of their homelessness and social isolation. Conclusion: The increase in deaths among unidentified men of working-age indicates the emergence of a health threat associated with homelessness and social marginalization. This vulnerable group is exposed to different levels and causes of mortality compared with the larger population and represent a new challenge that requires serious and immediate scholarly attention and policy responses.