Background : The characteristic of parkinson's disease is the accumulation of alpha-synuclein protein in neurons . Nortriptyline inhibits the accumulation of alpha-synuclein. In this article, the simultaneous effectiveness of nortriptyline in 3 different doses with levodopa and benserazide was investigated. Methods : In this study , 49 rats were randomly divided into 7 groups of 7. 5 groups were diagnosed with parkinson's unilaterally by injecting 6 - OHDA into the substantia nigra of the midbrain. 1 group was subjected to stereotaxic surgery, but 6 - OHDA was not injected and they did not have parkinsonism, and 1 group was kept healthy. of the 5 groups with parkinson's, the control group did not receive treatment, the other group was treated with levodopa at a dose of 10 mg/kg and benserazide at a dose of 2.5 mg/kg, and groups 3 to 5 received nortriptyline in doses of 5, 10 and 20 mg/kg in addition to levodopa and benserazide. behavioral changes were measured and recorded with elevated body swing test, open field and elevated plus maze ( EPM ). Results : The results showed that the best findings in terms of improvement of behavioral symptoms were obtained in the nortriptyline treatment group with a dose of 10 mg/kg along with levodopa and benserazide. Conclusion : The addition of nortriptyline, especially at a dose of 10 mg/kg to the treatment of levodopa and benserazide, in behavioral changes in rats that were treated with different doses of nortriptyline along with levodopa and benserazide, is significant, and the greatest effect is at a dose of 10 mg/kg of nortriptyline, and the behaviors they were less negative.