Background : Deflazacort is a new oxazoline derivative of prednisolone, and considered to have equal anti-inflammatory effect as and less metabolic side effects than prednisolone. In this multi-center controlled study, we tried to compare deflazacort with prednisolone in terms of the efficacy in rheumatoid arthritis as well as effects on bone metabolism, glucose metabolism, and endogenous cortisol secretion, and side effects. Methods : We randomly allocated patients with rheumatoid arthritis to either deflazacort or prednisolone. Patients were given 5mg/day of prednisolone(or equivalent dose of deflazacort with 6mg/day) at minimum. Dosage of each drug was titrated according to patient's symptom. Clinical parameters, such as height, weight, blood pressure, tender joint count, swollen joint count, and activity of daily living score, were measured at baseline, 1st, 3rd, and 6th month of treatment. Complete blood count, chemistry including liver function test, BUN/Cr, luting glucose, and urinanalysis were also done at baseline, 1st, 3re, and 6th month of treatment. Serum osteocalcin, 24 hour urine calcium, 24 hour urine deoxypyridinoline, morning cortisol, and glucose tolerance test were done at baseline, and 3rd month of treatment. Bone densitometry was performed at baseline and at 6th month of treatmnent. Results : Both deflazacort and prednisolone groups showed improvement in tender joint count, swollen joint count, activity of daily living score, Westergren ESR, and hemoglobin level. Degree of improvement was not significantly different between two groups. Changes of serum osteocalcin, 24 hour urine calcium,24 hour urine deoxyridinoline, morning cortisol, and glucose tolerance test were not significant during study period in both groups. Bone destiny at femur neck decreased significantly only in prednisolone-treated group. Frequency of side effect was not different in both groups. Conclusions : Efficacy of deflazacort was comparable to that of prednisolone. Bone loss as measured by bone densitometry was less in deflazacort-treated patients.