Introduction. Connective tissue is ubiquitous in the human body, hereditary connective tissue disorders affect several systems and organs, undifferentiated connective tissue dysplasia is often not diagnosed, proceeds under the guise of another pathology, and the pathogenetic basis of COVID-19 is a systemic disease associated with vascular inflammation and endothelial damage. The goal is to study the clinical and laboratory features of a new coronavirus infection in patients with connective tissue dysplasia.Materials and methods. The study included 117 patients diagnosed with a new coronavirus infection COVID-19 aged 35 to 65 years, hospitalized in an infectious diseases hospital City Clinical Hospital No. 40 in Ekaterinburg. The patients were divided into 2 groups: the main group (n=90) people with the stigmas of connective tissue dysplasia and the comparison group: (n=27) people without signs of connective tissue dysplasia. Inclusion criteria: the presence of stigma of connective tissue dysplasia, the presence of a confirmed infection with COVID-19 (PCR of nasopharyngeal and oropharyngeal swabs for SARS-CoV-2). Exclusion criteria: age over 65, comorbidities: diseases of the musculoskeletal system, chronic kidney disease, pregnancy, HIV infection, oncohematological and lymphoproliferative diseases.Results. The course of a new coronavirus infection against the background of connective tissue dysplasia is characterized by: 1) fever in 100% of patients; 2) damage to the lungs of more than 50% of the lung tissue with signs of respiratory failure in 63%; 3) a pronounced systemic inflammatory response syndrome, manifested by a significant increase in C-reactive protein and creatine phosphokinase.Discussion. An analysis of the results showed that one of the predictors of the severity of the course of COVID-19 infection may be the presence of connective tissue markers of dysplasia (odds ratio 7.4, 95% CI 2.6-21.3).Conclusion. The new coronavirus infection COVID-19 proceeds against the background of connective tissue dysplasia more severely with a pronounced intoxication syndrome with an early and longer manifestation of acute respiratory failure.