In the carrageenin-induced edema test in rats, the anti-inflammatory activity of SL-573 was 1.6 times as potent as those of phenylbutazone (PB) and ibuprofen (IP), 3.3 times as potent as that of mefenamic acid (MF) and 6.7 times as potent as that of mepirizole (MP). In the yeast-induced edema test in rats, SL-573 showed equipotent activity with IP, the activity of which was 4 times as potent as that of MP. In the dextran-induced edema test in rats, the anti-inflammatory activity of SL-573 was significantly higher than those of IP and MP. SL-573 showed no anti-inflammatory activity in the formalin-induced edema test in rats in the same way as seen with IP and MP. SL-573 markedly inhibited the increase in capillary permeability in mice induced by intraperitoneal administration of acetic acid, and its activity was 12 times as potent as that of PB and 17 times as potent as that of MF. SL-573 showed anti-granuloma activity neither systemically nor locally. SL-573 showed equi-potent activity with PB in the adjuvant arthritis test in rats and had little effect on the healing process of the skin wound in rats. The effect of SL-573 on the carrageenin-induced edema was not diminished in the adrenalectomized rats. The gastric bleeding effect of SL-573 was significantly weaker than that usually seen in nonsteroidal anti-inflammatory drugs. SL-573 did not induce intestinal perforation even at the high dose of 800 mg/kg. Additionally, SL-573 showed a protective effect on the indomethacin-induced intestinal lesions. These pharmacological profiles of SL-573 were considered to be quite characteristic as compared with those of known nonsteroidal anti-inflammatory agents.