Abstract The effects of FR167653, a dual inhibitor of interleukin (IL)-1 and tumor necrosis factor (TNF)- production, on the development of adjuvant arthritis were investigated in rats. Female SpragueDawleys rats weighing 130 g with adjuvant arthritis were administered FR167653 0.1, 1, 10, or 30 mg/kg, and their arthritis scores, soft tissue X-rays, and histological findings were then compared with those of a control group. Body weights were also recorded. FR167653 suppressed the severity of adjuvant arthritis in a dose-dependent manner. Administration of the drug had little effect on body weight. FR167653 might locally affect arthritic joints to prevent inflammation. However, further experiments are necessary to elucidate the underlying mechanisms.