The prevalence of multiple sclerosis in the south of Europe seems to be higher than previously considered. This study aimed to probe a possible increase in the prevalence of multiple sclerosis (MS) in Osona over the past 17 years. This was a cross-sectional study including MS-confirmed cases from several sources of information. Crude and adjusted prevalence rates were obtained. One hundred and twenty patients fulfilled the study criteria. The crude prevalence of MS was 79.9 (95% CI: 66.3-95.6) per 100,000 inhabitants and 91.2 (95% CI: 75.5-109.2) per 100,000 among Spanish born individuals. The prevalence of multiple sclerosis cases in Osona has increased over the past 17 years to being one of the highest reported in Spain.