Background and purpose: Rosa damascena Mill in Iranian folk medicine is used for treating digestive disorders. We assessed the antispasmodic effects of extract of the leaves of this plant on ileum contractions in Wistar rats; possible mechanisms were investigated, too. Materials and methods: In this experimental study, 48 male Wistar rats (150-200 g) were divided randomly into six groups of eight members, including control group and the groups received extracts of Rosa damascena Mill, propranolol, naloxone, L-nitro-arginine methyl ester (L-NAME), and calcium chloride. To evaluate the effectiveness mechanisms, ileum was placed adjacent to antagonist drugs of β-adrenergic receptors, opioid and inhibitor of the synthesis of nitric oxide, and also under the influence of different doses of calcium chloride. The observed effects were recorded. Then, the percent changes were calculated. Statistical analysis was done using parametric tests of repeated measuring design, ANOVA and t tests. Results: Cumulative extract of Rosa damascena Mill (100, 500 and 1000 mg/k) decreased ileum contractions induced by KCl (P < 0.0001). Propranolol and naloxone significantly decreased the inhibitive effect of the extract on contractions induced by KCl (P < 0.0010), but L-NAME was ineffective. Also, calcium led to the contraction of depolarized tissue through KCI and this contractile effect decreased significantly by the cumulative concentration of Rosa damascena Mill (P < 0.0010). Conclusion: Extract of Rosa damascena Mill probably decreases ileum movements of the rat through stimulating the β-adrenergic and opioid receptors and voltage-dependent channels, and it may be used to treat digestive disorders
