Several coumarin derivatives have been reported to present multiple biological activities and especially antiinflammatory/antioxidant activities. Recently the synthesis and in vivo/in vitro anti-inflammatory/antioxidant activities of several new coumarin derivatives with a 7-azomethine linkage have been reported. In the present study these derivatives were further tested for their antioxidant ability. Some of them were found in vitro to inhibit lipid peroxidation and to strongly scavenge superoxide radicals. Compound 3 was found to potently inhibit cyclooxygenase-1 (COX-1) and the yeast-induced rat paw oedema. The most active compounds within the set were tested against adjuvant-induced arthritis. Compound 3 was found to significantly protect the rats from adjuvant-induced arthritis (when it is administered from the first day or when it is administered the fourteenth day, with the first symptoms of the disease). An attempt was made to delineate the possible mechanism of action of the studied compounds.