Rheumatoid arthritis (RA) and osteoarthrosis (OA) are the most common diseases of the musculoskeletal system which cause an enormous medical and social harm on the patients and the society as a whole. The risk factors of the development of RA and OA are high atmospheric concentrations of silicon compounds (Si). The purpose and the objectives of the study were the assessment of the role of silicon microelementoses in RA and OA, the study of the influence of the level of air pollution with Si-containing pollutants in the regions of human habitation on the prevalence and nature of the disease. The study included 188 patients (83 with RA and 105 with OA), respectively, with an average age of 46 and 58 years old, in the proportion of men and women as 1:4 and 1:5, with the duration of the disease 9 and 10 years. Using the method of atomic absorption spectrometry we determined Si content in the blood serum and in the hair, we evaluated the level of the pollution with Si-containing compounds. It has been found out that RA is accompanied by reduced accumulation of Si in the hair in ¾ of the number of the patients on the background of the absence of the changes in cremnium level, and silicon imbalance was typical in OA which is manifested by increasing of Si content in the blood. A high level of Sicontaining compounds in the atmosphere of the residence regions of the patients with RA influences Si accumulation in the body which is an additional factor of the maxillary bone joints and large joints lesion, the appearance of systemic symptoms, aseptic osteonecrosis, intraarticular Goff and Shtaidy bodies. Air pollution with silicon pollutants affects negatively the incidence of OA in these regions which is accompanied by Si accumulation in patients’ hair with a subsequent impact on the rate of progression of articular syndrome, the development and the severity of subchondral sclerosis, ligamentosis of knee joints, reactive synovitis and cartilage flap bodies, and in relation to spondylopathy inhaled Si compounds have a certain protective action.