The oral anti-inflammatory activity of 4,4'-dihydroxy-alpha-truxillic acid (1) was compared with that of two other nonsteroidal anti-inflammatory drugs, loxoprofen sodium (LOX) and diclofenac sodium (DIC). The activity of 1 against the inflammatory pain response induced by formalin was comparable to that of LOX, but weaker than that of DIC. In the monosodium urate (MSU)-induced acute inflammatory model, 1 showed stronger anti-inflammatory activity than both LOX and DIC. The ED50 value for 1 was 4.5 micromol/kg, while the values for LOX and DIC were 65 and 25 micromol/kg, respectively. Otherwise, the oral single-dose toxicity of 1 was investigated in both sexes of Sprague-Dawley rats administered once at a dose of 2000 mg/kg. 1 showed no death, clinical signs, changes in body weight or pathological findings related to the treatment. In addition, no mutagenicity was observed in the reverse mutation assay. Furthermore, 1 did not show any ulcerogenic activity at doses ranging from 30 to 300 mg/kg in rat. Thus, 1 might be considered to be an effective anti-inflammatory agent with no deleterious adverse effect.