To evaluate the bone mineral density (BMD) in patients with rheumatoid arthritis (RA) treated with MTX or SF. The study consisted of 56 premenopausal women diagnosed with rheumatoid arthritis (RA). Bone mineral density (BMD) of the lower lumbar spine was assessed before starting treatment, and again after 12 months of treatment. DEXA scanning was used to evaluate BMD. Corticosteroids or other substances known to affect bone metabolism were not administered. 45 women completed the study, of whom 23 were treated using SF and 22 MTX. The average dosage of MTX used was calculated to be 590 mg. A significant difference in the BMD of SF and MTX patients was not observed in the pretreatment phase, nor after 12 months of treatment. However, in all patients a significant reduction of BMD was observed, irrelevant of the choice of drug. The average loss of bone mass was 1.7% and 1.4% in the MTX and SF groups, respectively. MTX therapy administered in low doses as assessed after 12 months did not cause a rapid decrease of bone density in patients with RA.