Systemic vasculitis refers to a group of rare diseases characterized by inflammation of blood vessel walls, which may cause ischemia and structural damage in various organs. Among large-vessel vasculitides, Takayasu arteritis primarily affects the aorta and its main branches, whereas Behçet's disease is a variable vessel vasculitis involving arteries and veins of all sizes. Both conditions can lead to multisystemic involvement and significantly impact physical and psychosocial health. This observational, case-control study aims to compare multiple physical and psychosocial parameters among individuals with Takayasu arteritis, Behçet's disease, and healthy controls. Assessments will include respiratory and peripheral muscle strength, functional status, exercise capacity, body composition, quality of life, illness perception, and psychological well-being. Measurements will be conducted using standardized clinical tests (such as maximal inspiratory and expiratory pressures, handgrip and limb strength dynamometry, squat test, and six-minute walk test) and validated questionnaires (Health Assessment Questionnaire (HAQ), the Short Form-36 Health Survey (SF-36), the EuroQol 5-Dimension 5-Level Questionnaire (EQ-5D-5L), and the Visual Analogue Scale (VAS)). The study seeks to identify differences between groups and provide a comprehensive understanding of how systemic inflammation in Takayasu arteritis and Behçet's disease affects physical performance, quality of life, and psychosocial health. These findings may help guide physiotherapy, rehabilitation, and multidisciplinary management strategies for patients with systemic vasculitis.