Rheumatoid arthritis (RA) patients have an increased prevalence of cardiovascular disease (CVD). Traditional cardiovascular risk factors do not fully explain this increased incidence. Cardio-respiratory fitness and obesity are acknowledged CVD risk factors; however these are generally excluded when assessing CVD risk in RA patients. This PhD thesis aims to investigate the association between cardio-respiratory fitness and traditional CVD risk factors in RA patients and establish whether exercise can improve these CVD risk factors. To determine cardio-respiratory fitness of RA patients a simple submaximal step test was validated (n=24). A cross sectional study was then carried out with 100 RA patients who underwent assessments of fitness (step test), RA disease, CVD risk factors and body composition. RA patient fitness level was poor (22 ± 6 ml·kg-1 ·min-1 ). Traditional CVD risk factors were not obviously elevated but poor fitness was strongly associated with poor body composition. Thirty-five patients were unable to complete the step test. These patients rated their arthritis as worse, more painful, disabling and had a greater prevalence of obesity. This study highlighted two important modifiable CVD risk factors (poor fitness and obesity) that are not routinely measured. An 8 week exercise intervention (n=10) designed to increase cardio-respiratory fitness was then implemented and improved cardiovascular health (systolic blood pressure), body composition (body fat, waist and hip circumference) and RA disease (p < 0.05). RA patients are suffering from the effects of being unfit and overweight. Not only are they independent CVD risk factors, they impact considerably on patients disease perception and functional ability. These risk factors should be considered as part of RA care and information should be provided to help patients improve their cardiovascular health and general wellbeing. Regular exercise can help improve the above CVD risk factors as shown in this thesis.