Among 138 inpatients with rheumatoid arthritis (RA) 18.1% had arterial hypertension (AH). AH in RA appeared in subjects with hereditary predisposition to AH. The presence of AH in RA is associated with rheumatoid vasculitis as the number of extraarticular manifestations of RA in AH patients is higher and is unrelated to renal affections. The levels of free radical lipid peroxidation in plasma and saliva are determined to a large extent by the hereditary factor in RA and are related to the presence of predisposition to AH.