Italy is currently regarded as a medium-frequency area for MS. In recent years, however, this opinion has been questioned by many. Current public health organization in Italy is inadequate for epidemiologic search, and accurate estimates of MS frequency are possible only as a result of intensive surveys of small population groups. To date, seven studies of this sort are available, which are comparable in suggesting that Italy also falls into the high-risk zone for MS. This paper reports the results of a similar survey in Barbagia, Sardinia, southern Italy. Based on 21 probable MS cases, the prevalence per 100,000 on December 31, 1975, was 40.7 (48.5 if age-and sex-standardized to the Italian population). This result gives further support to the possibility that Italy is a high-risk area for MS.