modern doctor of any specialty periodically encounters diseases, the recognition of which is very difficult, and any delay in diagnosis can lead to serious complications and even the death of the patient. Such diseases include systemic vasculitis. This is a diverse group of diseases whose common morphological sign is inflammatory or inflammatory necrotic lesion of the vascular wall, and clinical manifestations depend on the activity of the process, the type of the affected vessels, and also their localization. The article discusses the main difficulties in the diagnosis of systemic vasculitis, which the clinician may encounter in his practice, and suggests the main ways to overcome them.