Floctafenine has been studied in comparison with acetyl-salicylic acid, indomethacin and d-propoxyphene in a series of tests for analgesic and anti-inflammatory activity. It is very active in the acetic acid-induced writhing test and on the inflamed paw in the Randall and Selitto test. Furthermore, like acetylsalicylic acid and indomethacin, but unlike d-propoxyphene, it has no effect on the non-inflamed paw, and similarly it is inactive in the tail flick and in the hot plate test. Floctafenine is also very effective in some acute inflammations such as naphtoylheparamine-induced oedema or in UV erythema, but it is distinctly less active in carrageenin-induced oedema or in adjuvant arthritis. In rat gastric and intestinal mucosa its tolerance is excellent. It has no action on the central and autonomous nervous systems. The pharmacological profile of this compound thus places it amongst the non-narcotic analgesics. It has an exceptionally high therapeutic index, much higher than that of acetylsalicylic acid and indomethacin.