Rheumatoid arthritis (RA) is one of the most common chronic inflammatory disorders associated with enhanced cardiovascular morbidity and mortality. Established high prevalence of classical cardiovascular risk factors may only partly explain cardiovascular phenomenon in this disease. Emerging risk factors, markers of inflammation and prothrombotic state such as platelet size are believed to reflect activity of RA. We aimed to study mean platelet volume (MPV) in a cohort of patients with RA and to clarify possible effects of classical cardiovascular and RA-associated risk factors on MPV. Demographic, clinical and a wide range of laboratory parameters, including MPV and platelet count, were obtained for 400 RA patients. Platelet size and count were also assessed in 360 non-RA controls from the local population. We found significantly increased MPV in RA patients compared with controls (P=0.001). The difference retained significant after adjustment for age and sex. High values of MPV (>or=10.7 femtoliter [fL]) were more frequent in RA patients than in controls (21% vs. 9.2%; P