The article contains the review and analysis of data on the mechanisms of the toxic action of carbon nanotubes (CNTs) on the body and available results of CNT toxicological evaluation after inhalation and oral routes of the action. Identification of cellular and molecular mechanisms of CNTs toxicity allows to justify the list of the most sensitive biochemical toxicity markers that could be used for monitoring the occupational effects of CNTs and serve as a promising target for the corresponding pharmacological and immunopharmacological interventions aimed on specific prophylaxis and therapy of diseases caused by CNT. A considerable amount of experimental data obtained in vivo on inhalation animal models allows to establish the hygienic standardfor CNT in the air of the working area. As to safe levels of the oral route of CNT it needs further study for their reliable assessment. The search and selection of sources for the review was executed with the use of public databases, including (in order of relevance) PubMed, Scopus, Google Scholar, and RISC, for the period from 2004 to 2017.