We have investigated the effect of a novel anti-rheumatic drug, cis-2-(4-chlorophenyl)-4,5-diphenyl-2-imidazoline hydrochloride (TA-383), on macrophages. TA-383 (> or = 10(-9) M) significantly stimulated rabbit alveolar macrophage (AM) migration, and its migration-stimulatory activity was more potent than those of L-fucose (5 x 10(-3) M), lobenzarit disodium, bucillamine (SA-96) and salazosulfapyridine. In addition, TA-383 enhanced the production and/or release of macrophage migration enhancement factor by rabbit spleen cells. In vivo, TA-383 (0.4 mg/kg, p.o.) has suppressive effects on picryl chloride-induced delayed type hypersensitivity and type II collagen-induced arthritis in mice. These results suggest that the anti-rheumatic activity of TA-383 may be exerted through the dispersion of macrophages from inflammatory sites.