Indoxole is methoxyphenyl-indole derivative and cyclooxygenase inhibitor with potent anti-inflammatory activity. Indoxole is effective against carrageenin-induced edema in intact and adrenalectomized rats and in mice and gerbils. Oral potency varies from 0.9 to 5.0 times that of phenylbutazone and 3 to 15 times that of acetylsalicylic acid, depending upon the vehicle employed. In prevention and therapy of rat adjuvant arthritis, Indoxole is equipotent to phenylbutazone and more potent than acetylsalicylic acid. It does not produce water and electrolyte retention, thymolysis, adrenal hypertrophy, gastric ulcers, and slow reacting substance-anaphylaxis and bradykinin inhibition characteristic of phenylbutazone. Its spectrum of antiinflammatory and pharmacologic activity is narrower than that of hydrocortisone. Pharmacologically, it is similar to acetylsalicylic acid. Indoxole lowers yeast-induced fever in rats, prevents Proteus mirabilis-induced fever in dogs, inhibits phenylquinone-induced writhing in mice and increases the pain threshold in rats.