Multiple Sclerosis (MS) is the most common cause of neurological disability in young adults. It is estimated that more than two million people have MS worldwide. This study aimed to assess the incidence of MS and its associated factors in Shiraz, Southwestern Iran. Data related to the incidence of MS were obtained from the MS center of Shiraz University of Medical Sciences from 2001 to 2014. The study participants were all residents of Shiraz. The subjects were diagnosed with MS by neurologists (all newly diagnosed patients from 2001-2014) and were registered in
MS center to receive treatment. Descriptive statistics and univariate and multivariate Poisson regression analysis were done. During the study period, 2637 eligible patients were identified. The highest incidence of MS occurred in 2011 and 2012 (17.62, 95% CI: 8.02-38.72 and 16.92, 95% CI: 6.23-45.88 per 100,000 respectively).