Thirty-two patients with juvenile rheumatoid arthritis (JRA) entered a comparative, double blind, parallel 16-week clinical trial of azathioprine versus placebo. After 8 weeks of therapy the changes in disease activity measurements indicated an improvement in the azathioprine group compared to the placebo group. At the end of the study, most of the disease activity measurements were changed in favour of the azathioprine group compared to the placebo group, but statistically significant differences between the groups were found for only 2 disease activity measurements. Therapy was stopped for 2 patients in the azathioprine group because of reversible leukopenia. Our results and the risk for severe adverse reactions indicate that azathioprine remains a third line drug for patients with JRA.