A series of 4-hydroxy-(or-amino)-ethyl-amino butyrophenones or butyrothienones were synthesized. For detail studies on antiinflammatory effects, gamma-(2-aminoethylamino)-2-butyrothienone (gamma-ABT) was chosen as representative of these new non-steroidal anti-inflammatories (NSAID). The effect on mouse paw edema induced by various phlogistic agents was first investigated. The inhibitory effect of gamma-ABT on carrageenin-induced edema was remarkable and nearly equal to that of indometacin. Similarly to indometacin, gamma-ABT inhibited the early and late stage of yeast-induced edema in contrast to concanavalin A (Con A) induced edema which was only inhibited by gamma-ABT. Both the above induced edema are supposed to be unrelated to prostaglandins in the rat system. gamma-ABT displayed an inhibitory effect on nystatin-induced edema similar to indometacin suggesting that gamma-ABT has significant membrane stabilizing action and a strong blocking action on synthesis of prostaglandins. gamma-ABT inhibited as well the sustained edema induced by mustard. In conclusion gamma-ABT is an effective agent not only on acute but also on subacute and chronic inflammation and its mode of action appears similar to other NSAID. gamma-ABT posses in addition the advantage of antioxidant activity which is not shared by selective cyclooxygenase inhibitors and thus should be potentially effective in autoimmune diseases.