The acetic acid induced writhing response is a sensitive procedure to evaluate peripherally acting analgesics. The possible mechanism is thought to be mediated by inhibition of lipooxygenase and/or cyclooxygenase in peripheral tissues induced by acetic acid, thereby reducing PGE2 synthesis and interfering with the mechanism of transduction in primary afferent nociceptor (23, 24). Since the MeOH extract of A. ilicifolius significantly inhibited the acetic acid-induced writhing in mice it suggests that the analgesic effect of the extract may be peripherally mediated