Objective. The study objective is to evaluate the clinical and pathogenetic relationships of the inflammatory, oxidative and mixed molecular subtypes / endotypes of osteoarthritis. Methods. 65 patients with osteoarthritis of knee joints were examined: 8 men and 57 women, average age - 66.7 years, duration of the disease from 1 to 18 years. For the purpose of molecular phenotyping, the concentrations of interleukin-1 ß and oxidative-induced growth inhibitor-1 were determined in the blood serum and phenotypes of the osteoarthritis: inflammatory, oxidative and mixed were isolated. Results. Inflammatory endotypes occurred in 9, oxidative - in 28 and mixed - in 28 cases. The pain level, measured from the visual analogue scale, was the lowest in individuals with an inflammatory molecular subtype of the osteoarthritis. The overall score for the WOMAC questionnaire was significantly higher in patients with a mixed endotypes of the disease. The concentration of cartilage-associated protein was significantly lower in patients with inflammatory and oxidative molecular subtypes of osteoarthritis. The level of the Fas-ligand was significantly lower in the inflammatory subtype, and the level of endothelin-1 was lower in the oxidative subtype of the disease. The growth factor/differentiation-5 concentration was significantly higher in the group with the inflammatory osteoarthritis phenotype. Conclusions. The osteoarthritis is a heterogeneous disease; the variety of its manifestations depends on the molecular-transcriptom mechanisms and ways of responding to stress. Endotyping patients with osteoarthritis on molecular basis is justified from the clinical and pathogenetic point of view. Thus, the data obtained by us on the clinical and pathogenetic features of various molecular phenotypes of the osteoarthritis can form the basis of a personified approach in this disease.