There is information about side effects of tattoo caused both by skin injury and the effect of the dyes used. However, these data are scarce and contradictory, there is no classification of complications, which determines the relevance of this study. Objective — the study was aimed at systematizing tattoo complications, developing classification and preventive measures based on analysis of literature and our own clinical data. Material and methods. We analyzed publications in the PubMed (1997—2017) dealing with tattoo complications. We accumulated the database of clinical cases of complications after tattoo procedure. Clinical and laboratory diagnostics included history taking, examination, dermatoscopy, allergy tests, bacteriological examination, immunofluorescence tests, enzyme-linked immunosorbent assay, and histological examination of biopsy samples of tattooed tissue. Results. Compounds with pronounced toxic, mutagenic and carcinogenic effects were found in the pigments used for tattoos. Allergic reactions in the form of anaphylactic reaction (0.1%), urticaria (3%), contact dermatitis (19.9%), and eczema (7%) are the most common complication. There were cases of HIV (3%) and hepatitis (8%) infection. Secondary infection was observed in 15% of cases. Side effects were characterized by pronounced polymorphism (purulent-inflammatory, degenerative, necrotic, and neoplastic processes). We proposed a classification of tattoo complications based on the studies systematizing the available information about the side effects of tattoos. Conclusion. Given the invasiveness of the procedure and significant number of complications, the list of contraindications for the use of tattoo should be developed; mandatory certification of injected dyes should be used; standards for preliminary laboratory studies prior to this invasive procedure should be developed; higher requirements for specialists performing tattooing should be used; the workplace of a tattoo master should be certified with allowance for the compliance with aseptic and antiseptic techniques.