The doctorate paper “Research on the increase of wear resistance of contact surfaces of screw type compressor rotors” is aimed at the increase of service life of contact surfaces of screw type compressor asymmetric rotors. The work studies peculiarities of rotor designs, as well as studies and systematizes most characteristic compressor failures. The rotor material and characterising parameters were analysed looking for factors affecting the wear intensity of contact surfaces and rotor service life. The possibility to extend the stability of rotor wearing surfaces was analysed. The paper studies geometrical forms of rotor, mathematical coherences were established allowing to describe the rotor profile curves and make a shaping tool for any profile area under consideration to restore the screw type rotor profile, which essentially affects the compressor operation efficiency. The instrument design procedure is being presented. The rotor profile restoration possibilities are being analysed. Improvement of contact surface of oil flooded compressor rotor was carried out according to the chosen technology and parameters, changing characterizations of material’s upper layer mechanical properties, covering them with wear resistant TiN coatings. Measurements of characterizing properties of materials improved for experimental purposes and their statistical data processing were carried out, as well as analyses of contact surface condition both on micro and nano levels. Data comparison methods have been developed according to several criteria, introducing parameter coefficients: 1) Criterion based on the contact type of rotor surface – contact type coefficient kT; 2) Criterion considering the wear process course – wear impact coefficient kd. Theoretical comparison of changes of rotor materials characterising parameters was performed to assess the efficiency before the development of technological processes. The Doctorate paper has been made in the Latvian language and consists of Introduction, five chapters, work conclusions, appendix, list of used information sources, summary, 97 figures, 35 tables, constituting altogether 123 pages. The list of used information sources includes 74 titles.