Multiple Sclerosis is a condition of demyelination of the nerve cells in the brain and spinal cord. It is possible that multiple factors are involved in causing multiple sclerosis, including DNA defects in nuclear and mitochondrial genomes, viral infection, hypoxia, oxidative stress, lack of sunlight, and increased macrophages and lymphocytes in the brain. This metaanalysis has gone through many researches and reviews to find the similarities and differences in the cause of this disease. The role of mitochondrial metabolism, environmental temperature and distance from the equator has been discussed in this research, and the amounts of Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS) has been found to be the most possible cause of multiple sclerosis in men and women.