Rheumatoid arthritis (RA) is associated with premature mortality, with approximately 50% of deaths being due to cardiovascular disease. It has been shown that the increased incidence of cardiovascular disease is independent of traditional risk factors. Previous studies have shown an increased risk of coronary heart disease with increased levels of activated factor XII (FXIIa). The aim of this study was to investigate levels of FXIIa in patients with RA. We studied 32 patients with RA and 30 age- and sex-matched control subjects. We found FXIIa levels significantly increased in the patient group, with 56% of the patients and 6.7% of controls having levels greater than or equal to 2 ng/ml. A previous study has shown that individuals with levels of 2 ng/ml or more have an increased risk of coronary heart disease. Measurement of FXIIa could perhaps help to identify an 'at risk' group of patients, allowing early intervention therapy.