Seventy-four children with juvenile chronic arthritis were admitted to a 6-month multicentric double blind comparative study of the efficiency of D-Penicillamine or placebo. The results evaluated in 55 patients who completed the study, indicated an improvement in the total number of stiff joints and in the total index of severity measuring joint pain and inflammation. A significant reduction of the concurrent use of non steroidal antiinflammatory drugs was also observed. The tolerance was good except in two patients. Some children in the placebo group exhibited a definite improvement.