Fepradinol is an effective non-steroidal anti-inflammatory agent. The effect on rat paw oedema induced by various phlogistic agents was investigated. The inhibitory effect of fepradinol (25 mg kg-1, p.o.) on dextran-induced oedema was nearly equal to that of cyproheptadine (10 mg kg-1, p.o.). On oedema induced by platelet-activating factor only fepradinol (25 mg kg-1, p.o.) and phenidone (100 mg kg-1, p.o.) clearly inhibited the inflammatory process. Both the above induced oedemas are thought to be unrelated to prostaglandins in the rat system and therefore, the anti-inflammatory activity against them is not shared by selective cyclo-oxygenase inhibitors. Fepradinol (25 mg kg-1, p.o.) displayed an inhibitory effect on the early and late stage of kaolin- and nystatin-induced oedemas in contrast with indomethacin (10 mg kg-1, p.o.) and piroxicam (10 mg kg-1, p.o.) which only inhibited the late stage. The results obtained in this study confirm that fepradinol is a potent anti-inflammatory agent and indicate that its mechanism of action is different from that of other anti-inflammatory compounds.