INTRODUCTION

Since the first survey of multiple sclerosis in Iceland, covering 1946-1955, was performed by Gudmundsson and Gudmundsson (1962), the author has endeavoured to follow up this work and to revise the case records in order to evaluate the degree of accuracy of the survey methods. Some cases not fulfilling the diagnosis of multiple sclerosis during the collection of cases in 1957-1961, have now in October 1969 proved acceptable. Other cases considered unlikely and rejected from the former study have been accepted. A few cases, on the other hand, have been discarded on clinical or histological grounds. Some possible cases have been transferred to probable or definite multiple sclerosis and some formerly probable cases reclassified as possible. Many new patients were gradually discovered and could be added to the original survey. The 6 year interval between prevalence day and cessation of collection of cases can be considered too short. The investigation had the additional purpose to provide information on survival, mortality rate, familial incidence, degree of disability and finally some natural characteristics of multiple sclerosis in Iceland. This study is comparable to the re-evaluation of the Winnipeg-study by Stuzio et ul. (19641, with the exception, that no attempt has been made to elucidate the prevalence rate on the prevalence day of the follow-up study, i.e.: 1 Oct. 1969.