The publication is devoted to a large group of connective tissue diseases, contains modern information on the prevalence, etiopathogenesis, clinical manifestations, diagnosis and principles of treatment of such diseases as dermatomyositis (polymyositis), systemic lupus erythematosus, systemic scleroderma, Sjögren's disease, polymyalgia rheumatica and systemic vasculitis . Particular attention is paid to the classification of the diseases under consideration, the international criteria for their verification, as well as the prevention of their occurrence and clinical examination.The guide is intended for rheumatologists, therapists, general practitioners (family doctors) and medical students.