The therapeutic activity of tenoxicam, a thienothiazine derivative with analgesic and anti-inflammatory properties, has been studied by 15 investigators in Argentina and Brazil. Twenty-nine clinical trials were performed in a total of 747 patients suffering from rheumatoid arthritis (270), cox- and gonarthrosis (190), extra-articular inflammation (250) and acute gout (37). Out of the patients studied, 507 received tenoxicam and 240 were given comparative preparations. In 76% of the patients 20 mg tenoxicam was given as a single daily dose. In most patients duration of treatment was either six weeks or six months. Therapeutic results were evaluated according to the evolution of pain in various conditions as well as that of the articular, clinical and functional status. Once treatment was concluded a global evaluation of efficacy and tolerance was performed. The statistical analysis showed a significant improvement, in comparison to baseline, in all parameters considered under the different conditions. Double-blind studies showed no significant statistical differences between tenoxicam and the comparative preparations. Tolerance to tenoxicam was considered excellent, granting that some patients referred to adverse effects of the gastrointestinal type, such as epigastric discomfort, pyrosis and flatulence of moderate intensity. Tenoxicam is a new non-steroidal anti-inflammatory compound which is well tolerated and has excellent activity in the treatment of diverse rheumatoid conditions.