Multiple sclerosis (MS) is a chronic neurologic disease of unknown etiology, which shows a peculiar pattern of prevalence in the world, varying among different countries and regions of a particular country. The aim of the study was to assess the prevalence and incidence of MS in the Bjelovar-Bilogora County in the last two decades (1982-2001), including the period of war in Croatia. Retrospective analysis of a database containing medical history of 71 patients using Poser's criteria revealed the prevalence and incidence of MS to have significantly increased during the study period, in the years preceding the war in particular. At the beginning of the study period (1982), the prevalence of MS was 13.38/100,000, ranking the County an area of moderate risk, whereas at the end of the study period (2001) the prevalence of MS was 47.36/100,000, characterizing the County as an area of high risk of MS. In the first and last 5year period, the incidence was 0.53 and 2.40, respectively, showing a female predominance (F:M: 2.40:1). According to Poser.s criteria, the relapsing remitting type of disease was present in 54%, secondary progressive in 21% and primary progressive in 17% of patients, whereas 8% of patients remained unclassified. Optic neuritis was found in 14.96% of study patients. The mean age at disease onset was 32.5 years. The study showed the County to have become an area of high risk of MS in the last decade of the twentieth century.