Objective: In this study we investigated the epidemiology of MS and some related environmental factors in Kerman province, southeastern Iran. Methods: The MS diagnosis was based on the revised Mc-Donald criteria. The patients were those registered at the Iran MS society, Kerman branch; those in the MS registration centers of Kerman and Rafsanjan University of Medical Sciences, and the Department of Neurology at Shafa Medical Center were studied. Results: The prevalence of MS was 31.5 per 100,000 population in Kerman province, and 57.3 per 100,000 population in Kerman city. The male to female ratio was 1:3. Average age at onset was 28.35 years, and 3.9% of cases were early onset at ≤16 years of age. A linear relationship was observed between prevalence and average environmental temperature as prevalence tended to be lower in areas where the annual average temperature was higher. However, in the town of Shahrbabak which has cold weather, prevalence was low, which might be related to the presence of copper in this area. Average disability was 4.5± 1.9 (4.83 ± 1.9 in men and 4.26 ± 1.8 in women, p=0.0035) on the Kurtzke Disability Status Scale. The mean duration of illness was 8.2 ± 1 year. Almost all patients in this study used beta-interferon for a period of at least 4 years. Conclusion: The prevalence of MS in Kerman province was 31.5 per 100,000 people. A linear relationship between an increase in prevalence and low average temperature was observed. Copper may have a preventive effect.