An increasingly higher mortality rate due to diseases related to injection drug use is reported in the literature. However, the relevant diagnostic criteria and ICD-10 coding methods are incompletely explicated in the current publications, the proposed approaches are contradictory, and their practical application encounters difficulties. Results of autopsy of 100 drug addicts were used to obtain detailed macro- and microscopic picture of pathological changes in their organs, develop a diagnostic algorithm and classification of clinical signs. Recommendations on the documentation of forensic medical diagnosis and death certificates are presented. ICD-10 coding procedures are considered. Results of the study may be useful for raising awareness of thanatologists and histologists about injection narcomania, its clinical manifestations, diagnostic tools, and risk of HIV infection.