and Objective: Hydroalcholic extract of Peppermint is traditionally used for gastrointestinal disorders. This study was done to evaluate the effect of Peppermint extract on the mice colon motor activity following immobilization stress. Methods: In this experimental study, 30 male Albino mice were randomly allocated into the three groups; including control, stress and stress + Peppermint oil groups (n=10). The second group as a stress group exposed to immobilization stress for four hours during

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... hree days. Third group as stress plus Peppermint oil group was exposed to stress in addition to administration of 27 mg/kg/bw Peppermint oil intraperitoneally prior to stress. After three days, intestinal and peristaltic activity was recorded using pressure transducer from in vitro segments of colon (4-5 cm in length. Also, fecal weight, food intake and body weight was measured for each mouse for in vivo condition. Results: The mean±SD of fecal weight after three times stress immobilization was 1.36±0.71, 1.06±0.6 and 0.47±0.39 gr in control, stress and Stress + Peppermint oil groups, respectively (P<0.05). The mean±SD of internal luminal pressure after three times stress immobilization was 4.47±1.15, 3.48±1.25 and 0.77±0.37 mm/hg in control, Stress and stress + Peppermint oil groups, respectively (P<0.05). Conclusion: Peppermint oil is a strong inhibitor for colon motor activity following immobilization stress.