Highly significant improvement of symptoms was found during treatment with clofezone (Perclusone) over a period of 4 weeks in 56 in-patients with various rheumatic diseases, particularly rheumatoid arthritis (RA), ankylosing spondylitis (AS), and lumbar and cervical syndromes. During the first week clofezone was given at a daily dosage of 1200 mg and thereafter 600 mg. At the same time 21 of the patients with RA and 13 with AS received ACTH injections (0.25 mg twice a week). Already after the first week of treatment a highly significant decrease of disease activity was noticed, as judged by the amount of pain, inhibition of movements, joint swelling and erythrocyte sedimentation rate. The latter decreased on an average by 50% during the treatment period indicating a reduction of the inflammatory process. 51 of the 56 patients showed a satisfactory to very good tolerance of the treatment. Clofezone was discontinued in 5 patients during the first week, because gastro-intestinal intolerance occurred with the 1200 mg dosage. One of these 5 patients tolerated the smaller dosage later. As 3 of the 5 patients belonged to the RA and AS groups, the ACTH administration also has to be considered with regards to the intolerance. Because of possible side effects the higher dosage of clofezone should be given as short term treatment of highly active disease processes only. Clofezone reduced the serum uric acid level in 38 of 45 patients. Pathologically increased levels were reduced to normal in 15 of 17 patients.