Rheumatoid arthritis (RA) patients are characterized by increased arterial stiffness, an independent predictor of cardiovascular risk. It has been suggested that osteopontin (OPN), a cytokine involved in RA pathogenesis, might have vascular effects. To study a possible relationship between OPN and arterial stiffness, aortic pulse wave velocity (PWV) was measured by tonometry in 69 patients (41 with RA, 28 with systemic sclerosis [SSc]) and 18 healthy controls. Plasma OPN levels, oxidative stress markers, and endothelin 1 (ET-1) were assessed. OPN levels were significantly (P < 0.05) higher in RA (median 9.93, range 4.36-47.80 ng/mL) than in SSc (4.3, 2.1-19.7 ng/mL) or controls (5.2, 4.1-9.4 ng/mL). In RA patients, log-OPN was related to log-C-reactive protein (log-CRP) (r = 0.30, P < 0.05), age (r = 0.38, P < 0.01), Health Assessment Questionnaire (HAQ) (r = 0.58, P < 0.0001), and inversely related to total cholesterol (r = -0.33, P < 0.05) and apolipoprotein A (apoA) (r = -0.58, P < 0.001), but not to oxidative stress markers and ET-1. PWV was similar in RA (median 8.1, range 4.7-16.4 m/s) and SSc (median 8.7, range 7.1-13.1 m/s), but significantly greater (P < 0.01) than controls (median 7.5, range 4.1-10.4 m/s). Aortic PWV was related to log-OPN (r = 0.40, P < 0.01) only in RA patients. It also was related to age (r = 0.34, P < 0.05), mean blood pressure (r = 0.44, P < 0.001), and HAQ (r = 0.48, P < 0.001). In multiple regression analysis (r(2) = 0.36), including confounders, log-OPN remained a significant predictor (P < 0.05) of PWV in RA. Elevated plasma OPN levels are associated with increased arterial stiffness in RA patients, suggesting that this protein might represent a bridge protein between inflammation and the consequent joint damage and cardiovascular risk in RA patients.