Two hundred and ninety-six patients were enrolled in a 6-month, open-label tolerability study of enteric-coated naproxen in patients with rheumatoid arthritis (n = 174) and osteoarthritis (n = 122). Thirty percent of the patients were greater than 65 years of age. Under standard clinical prescribing conditions, enteric-coated naproxen 500 mg twice daily and 375 mg twice daily demonstrated an acceptable tolerability profile that was not different from what one would expect with standard naproxen.