A series of 2, 6-di-tert-butylphenols with azoles at the 4-position was synthesized and evaluated for anti-arthritic activity in adjuvant-induced arthritis (AA) assay. Some compounds were also examined for anti-inflammatory activity in carrageenin-induced rat paw edema assay (CIPE) and for analgesic activity in AcOH-induced writhing assay in mice. 4-(3, 5-Di-tert-butyl-4-hydroxyphenyl)-5-methyl-2-oxo-4-imidazoline (6b) (25mg/kg. p.o.) had about the same activity as indomethacin (2mg/kg, p.o.) in AA assay. Compound 6b (25mg/kg, p.o.) was as potent as phenylbutazone (50mg/kg, p.o.) and indomethacin (3mg/kg, p.o.) in CIPE and showed low acute toxicity (>1000mg/kg, mouse, >400mg/kg, rat). Compound 6b had radical-scavenging activity in vivo and in vitro, and showed mild inhibitory activity on delayed-type hypersensitivity. Thus 6b is a promising candidate as a new anti-arthritic agent. Detailed pharmacologic studies of 6b are under way.