The urinary excretion of proteins, N-acetyl-3-glucosaminidase and leucine aminopeptidase, was measured in 50 patients with rheumatoid arthritis (RA), of whom 20 subjects were on nonsteroidal anti-inflammatory drugs (NSAIDs) and 30 on gold salts. No pathological changes of the above-mentioned urinary parameters have been observed in the group of RA patients, in comparison with control subjects and patients suffering from osteoarthritis treated with NSAIDs.