We have examined the incidence of the Guillain-Barré syndrome (GBS) in the county of Hordaland. We have previously reported a marked increase in the incidence of MS in the same population. 109 GBS-patients were diagnosed in the period 1957-1982 according to the criteria of NINCDS. The annual incidence rates were stable over time with an average incidence of 1.2 per 100,000 population per year. The male/female ratio was 1.7. No statistically significant difference in incidence was found between urban and rural areas. We found an increasing incidence with age, more marked among males than among females. A predilection for GBS to occur in the colder half of the year was also found. 57% of the patients reported an antecedent infection less than 4 weeks prior to the onset of neurological symptoms. The stable incidence rates for GBS over time in contrast to an increase in the incidence of MS in the same population, indicates that different pathogenetic mechanisms are important in the two demyelinating diseases.