A double-blind crossover trial of bumadizone calcium (Eumotol), a non-steroidal anti-inflammatory drug, has been carried out in 56 patients with rheumatoid arthritis. On both objective and subjective criteria bumadizone was superior to placebo and paracetamol at a statistically highly significant level (P less than 0,01). When tested against acetylsalicylic acid, bumadizone was more effective in 13 patients and less effective in 4 patients. Although this does not represent a statistically significant difference it does suggest that its anti-inflammatory and analgesic qualities are at least equal to those of salicylate in high dosages. There were no serious side-effects in the patients who received bumadizone and the drug was better tolerated than either acetylsalicylic acid or paracetamol.