Twenty patients with classical or definite rheumatoid arthritis were treated with D-Penicillamine. Favorable responses were observed in 75% of the patients. Significant improvement in clinical parameters, such as ESR, CRP, titers of rheumatoid factor and so forth, was noticed in twenty weeks of treatment. Withdrawal from penicillamine treatment was necessitated in four patients because of adverse reactions to the drug. Untoward effects included skin rash (most frequent), pruritis and loss of taste. From this preliminary study we presume that in earlier cases in which rheumatoid lesions may be reversible, more favorable clinical effects would be expected from this agent.