Running title: Anti nociceptive, Pelargonium graveolens Abstract: Introduction: Pain is a somatosensory sense that as an indicator to diagnoses for diseases . Pelargonium graveolens is known as a medicinal plant with use in traditional medicine. The aim of this study is to evaluate the analgesic effect of Pelargonium graveolens leaves extract (PGE) in male mice Material and Methods: In this experimental study, 42 male mice were divided in 6 groups (n=7). The control group(taking normal saline,0.25 ml, i.p), morphine group( 1mg/kg, i.p), treated groups with PGE at doses of 100, 200 and 600mg/kg and group induced with naloxone (0.1mg/kg, i.p) + 200mg/kg of PGE. In order to evaluate the analgesic effects of PGE the tail flick and writhing tests were used. The data for each test were compared with One-way ANOVA and Tukey's post test. Results: Our results showed that PGE (200 and 600 mg/kg) increased pain thershold compared with control group in writhing and tail flick test significantly (P<0.001). Conclusion: The PGE has anitinociceptive effects in male mice. This analgesic effect of Pelargonium graveolens extract probably related to its flavonoids composition which has effect on opioid system.