A mortality study on Multiple Sclerosis (MS) was carried out in the province of Ferrara, Northern Italy, over the years from 1968 to 1989 (mean population 382,379 inhabitants) to outline the temporal trend of the disease in the residing population that can be regarded as a representative sample of the caucasians of Northern Italy. Given the difficulties in performing retrospective incidence studies over long time periods, the mortality rate was used as an indirect indicator of MS occurrence. Through a review of mortality tabulations with 340-345 ICD code and an intensive survey of all the MS cases, with successive check of the deceased ones at the general register offices of the study area communes, 56 MS patients who had lived and died in the province of Ferrara in the period 1968-1989 were selected with an average crude death rate of 0.67 per 100,000 per year (95% confidence interval: 0.51-0.87), 0.55 per 100,000 if adjusted to the Italian population. The death rate was stable over the considered time period with only a slight but insignificant increase in the last years of the survey. No differences were found among the rates from the 5 Local Health Units (USLs) in which the study territory is subdivided. The highest age-specific death rates were in the fifth and sixth decade of life and the average duration was 21.17 +/- 11.05 years. The results are consistent with a relatively stable MS risk in the population of the province of Ferrara and a homogeneous occurrence of the disease in the study territory.