Efficacy and practicability of a defined dosage scheme for interferon gamma was proved during one year's treatment in patients with rheumatoid arthritis. Interferon gamma was well tolerated. It was effective in improving blood sedimentation rate, anemia, leucocytosis and thrombocytosis as well as clinical parameters such as pain, mobility, swollen joints and morning stiffness. Concomitant medication with corticosteroids could be reduced.