Introduction: Nonsteroidal anti-inflammatory drugs (NSAIDs) are one of the most widely used drugs in the treatment of pain and inflammation. Although, their side effects i.e.; gastrointestinal and renal adverse effects, limit the use of these drugs. Therefore, investigating new compounds with higher efficacy and fewer side effects is considerable issue. In this study, the analgesic activity of rosmarinic acid at different doses was compared with piroxicam (known standard NSAID).Methods: To evaluate the analgesic effects of rosmarinic acid, two well-known methods, Hot plate, and Tail-flick, were used. The experiments were performed in 10 groups (6 male mice per group) including the experimental groups (rosmarinic acid), the positive control group (piroxicam), and the negative control group (normal saline). All administrations were through intraperitoneal injection. The obtained data were analyzed separately by SPSS software and an independent student t test.Results: Rosmarinic acid at doses of 10 mg/kg and higher had significant analgesic effects compared with the control group, 30 minutes after injection in both hot plate and tail flick tests (P < 0.05). Concomitant injection of 50 mg/kg of rosmarinic acid with 15 mg/kg of piroxicam produced significant painkiller effects when compared with the dose of 15 mg/kg piroxicam injection alone.Conclusion: Rosmarinic acid was able to exert analgesic effects in pharmacological tests in a dose-dependent manner. Concomitant use of rosmarinic acid and piroxicam may lead to synergic pain relief, especially in acute and severe pain in patients, reducing the therapeutic dose of piroxicam and subsequently, its side effects.