In an open study, the effect of sulfasalazine was evaluated in the treatment of juvenile chronic arthritis (JCA). Forty-one patients, i.e., 27 boys and 14 girls with JCA under 16 years of age, were included in the study. In all of them, treatment with nonsteroidal antiinflammatory drugs (NSAID) had been unable to control the disease. The patients were divided in 4 subgroups depending on the mode of onset and evolution (Type I = systemic onset, Type II = polyarticular form. Type IIIa and Type IIIb = pauciarticular form). Remission was achieved in 21 patients, significant improvement in 12. Status was unchanged in 4 patients and worsened in 3. In 5 patients side effects were observed, which forced interruption of treatment in 4. Sulfasalazine was stopped in 7 patients: for toxicity in 4 and for inefficacy in 3. In 7 other patients the treatment was terminated after a prolonged remission. These promising results must be confirmed in a double blind versus placebo study, preferably restricted to type III JCA.