This article investigates a tattoo as a component of non-verbal semiotics of medical discourse in pathological anatomy. The purpose is to estimate the diagnostic value of tattoos on the body of patients as semiotic and symbolic aspect of medical communication. Tattoos are classified into three types: image tattoos, feature tattoos, and conventional tattoos (symbolic tattoos). Conventional tattoos are the most informative component of medical discourse symbolics because of their diagnostic value. During the investigation it has been found out that criminal tattoos have the greatest value because of their structuring, clear connection with certain diseases (tuberculosis, liver cirrhosis), and also valuable are tattoos related to drug and alcohol addiction, which are characteristic for patients with viral hepatitis, osteomyelitis.