The aim of this clinical, endoscopical study was to evaluate the therapeutic efficacy and the gastric tolerability of etodolac, a new anti-inflammatory, non-steroidal drug, compared with naproxen. The study was conducted on 48 patients suffering from rheumatoid arthritis. 44 of whom completed the trial. After an initial oesophagogastroduodenoscopy to exclude the presence of gastric mucosal lesions, patients were randomly allocated to double-blind treatment with either etodolac 200 mg b.i.d. or naproxen 500 mg b.i.d. for a period of 4 weeks. Endoscopic control followed this treatment period. Both drugs proved effective in relieving clinical symptoms, without a statistically significant difference. Gastric mucosal lesions were observed in 15% of etodolac-treated patients and in 46% of patients treated with naproxen (P less than 0.05) (95% CI 0.01-0.60). Painful dyspepsia was observed in 15% of patients treated with etodolac vs. 38% of patients on naproxen therapy. This study demonstrates that etodolac is at least as active as naproxen in relieving rheumatic symptoms, and its administration results in a significantly lower degree of gastric damage.