Campylobacter jejuni was isolated from stool cultures from 14 (30%) of 46 patients with Guillain-Barré syndrome and from 6 (1.2%) of 503 healthy persons, and the difference was highly significant (p < 0.0001). In addition, serological evidence of recent C. jejuni infection was found in 5 of 29 patients with negative stool cultures. Therefore, 41% of patients were associated with C. jejuni infection. Ten of 12 (83%) isolates from patients with Guillain-Barré syndrome belonged to Penner serogroup 19, which is a rare serogroup in sporadic patients with C. jejuni enteritis. In the lectin typing study, all serogroup 19 strains from patients with Guillain-Barré syndrome were shown to contain terminal beta-N-acetylglucosamine residues on their cell surface, but serogroup 19 strains from patients with enteritis were not.