BACKGROUND: The risk of coronary heart disease (CHD) is increased in rheumatoid arthritis (RA). The reasons for this remain unknown, but traditional risk factors for CHD identified in the general population may be important contributors. OBJECTIVE: To assess comparatively the prevalence of traditional CHD risk factors and the absolute 10-year CHD risk in patients with RA or osteoarthritis (OA) without known cardiovascular co-morbidity. METHODS: Consecutive Caucasian hospital outpatients with RA (n = 150) or OA (n = 100) aged 40-75 years were assessed for known cardiovascular co-morbidity, age, sex, smoking status, presence of diabetes mellitus (DM), height, weight, systolic blood pressure (BP), total cholesterol (TC) and HDL cholesterol. Absolute 10-year CHD risk for each individual was calculated using the Joint British Societies CHD risk calculator. RESULTS: Prevalence and distribution of known cardiovascular co-morbid conditions were similar in RA (56/150, 37%) and OA (34/100, 34%). The resulting subgroups of patients without known co-morbidity (RA: n = 94; OA: n = 66) were not significantly different for age, sex, DM, smoking, systolic BP or TC: HDL cholesterol ratio. There was no significant difference in the absolute 10-year CHD risk between RA and OA (15.6+/-11.0 versus 14.8+/-9.3, p = 0.63). However, a significant proportion of patients without known cardiovascular disease in both the RA and OA subgroups had a 10-year CHD risk above the 15% or 30% risk levels, indicating the need for possible or definite intervention respectively. Over 80% of RA patients had at least 1 CHD risk factor that could be modified. CONCLUSION: Absolute 10-year CHD risk was not different between RA and OA patients in this study. Substantial numbers of RA and OA patients have potentially modifiable CHD risk factors present. We suggest that CHD risk should be assessed and modifiable risk factors addressed in the routine rheumatology clinic setting.