Anti-inflammatory properties of a newly synthetized compound, 6-chloro-4-oximino-1-phenyl-1,2,3,4-tetrahydroquinoline (M-7074), have been investigated. Anti-edema activities of M-7074 were more potent than those of phenylbutazone in carrageenin, bradykinin and mustard edema tests in rats. M-7074 showed an inhibitory effect on adjuvant arthritis, especially on the secondary inflammatory lesions in rats. Inhibitory effect of M-7074 on cotton-pellet granuloma formation was all but equal to that of phenylbutazone in rats. M-7074 also showed inhibitory effects on ultraviolet erythema in guinea-pigs and increased vascular permeability in mice, moderate analgesic activity in rats and mice, and antipyretic activity in rats. Furthermore, inhibitory effects of M-7074 on prostaglandin biosynthesis in guinea-pig lung homogenate and arachidonic acid-induced aggregation of rabbit platelets were fairly equal to those of indomethacin. However, M-7074 showed no effect on humoral nor cellular immunity in mice. M-7074 possessed no ulcerogenic activity in rats and mice, and LD50 value of M-7074 was 8.01 g/kg, p.o. in mice. These data indicate that M-7074 is a novel anti-inflammatory agent with large margin of safety.