This investigation was conducted to evaluate the tissue kallikrein activity in the synovial and paw tissues of control, non-treated adjuvant arthritic and adjuvant arthritic rats treated either with indomethacin or prednisolone. Adjuvant arthritis was induced in male Sprague-Dawley rats in the right knee by injecting 0.05 ml of a fine suspension of heat-killed Mycobacterium tubercle bacilli in liquid paraffin (5 mg/ml). Indomethacin (2.5 mg/kg given orally) and prednisolone (3.0 mg/kg given orally) treatment for 9 days caused a significant reduction (P < 0.001) in knee swelling. In non-treated adjuvant rats, synovial tissue kallikrein levels were raised (P < 0.01) than the synovial tissue kallikrein obtained from control normal rats. Prednisolone treatment resulted in reduction (P < 0.05) and indomethacin treatment produced raise (P < 0.01) in synovial tissue kallikrein levels. In non-treated arthritic rats, the paw tissue kallikrein levels were lower (P < 0.001) than the control rats; whereas, rats treated with prednisolone and indomethacine showed higher levels (P < 0.05) of paw tissue kallikrein. These results may suggest that the prednisone and indomethacin differ in their actions in inflamed synovial tissue kallikrein and have a similar effect in non-inflamed paw tissues.