Diseases and disorders such as neurodegenerative disorders are becoming more common as the world's population grows. Reactive species damage to the mitochondria is the primary cause of the dramatically rising number of neurodegenerative disorders. Free radical are most dangerous species than we think, Free radicals are molecules that have an electron that is not coupled with another electron. These compounds are extremely reactive because they include a free electron that is not coupled with another electron. Based on their centre chemical moiety, there are two main types of free radicals i.e. Reactive oxygen species and Reactive Nitrogen species .In general, free radicals form in three stages: initiation, propagation, and termination. Oxidative stress, defined as a disturbance in the balance between the production of reactive oxygen species (free radicals) and antioxidant defence, leads to damage to cells via different pathways. In this review article we focus on free radical role in neurodegenerative disorder and approaches toward free radicals.