Bone mass measurements were performed in a group of 30 ambulant, non-steroid treated female patients with rheumatoid arthritis (RA) of relatively short duration (mean 4.9 years). The bone mineral density (BMD) of the lumbar spine and femoral neck was assessed by dual-energy x-ray absorptiometry (DEXA), and related to parameters of disease activity and severity. Lumbar BMD was within the range of normal while femoral BMD was decreased compared to age-matched controls. BMD values, expressed as the percentage of age-matched healthy controls (BMD%), were positively related to the body mass index and negatively related to the number of swollen joints, the erythrocyte sedimentation rate and the platelet count. No relation was found between the lumbar and femoral bone mass on the one hand and disease duration, number of disease modifying anti-rheumatic drugs ever used, Ritchie articular index, C-reactive protein, functional ability or radiological scores on the other. It is concluded that in ambulant non-steroid treated female RA patients lumbar bone mass as measured with DEXA is within the range of normal, while femoral bone mass is slightly reduced. Both lumbar and femoral bone mass are related to the body mass index and parameters of disease activity.