The serum antibodies to N-acetylgalactosaminyl GD1a (GalNAc-GD1a) and other gangliosides as well as to Campylobacter jejuni were determined in 147 patients with Guillain-Barré syndrome (GBS). We found a distinctive clinical pattern in patients with anti-GalNAc-GD1a antibodies compared with those without the antibodies, that is, lack of cranial nerve involvement (87% versus 38%), distal-dominant weakness (80% versus 25%), and no sensory disturbance (73% versus 22%). The frequency of distal-dominant weakness was significantly higher in patients with both C. jejuni infection and anti-GalNAc-GD1a positivity (100%) than in C. jejuni-negative/anti-GalNAc-GD1a-positive (25%), C. jejuni-positive/anti-GalNAc-GD1a-negative (32%) and C. jejuni-negative/anti-GalNAc-GD1a-negative patients (20%). Lack of cranial nerve involvement and sensory disturbance were found in most C. jejuni-positive/anti-GalNAc-GD1a-positive and C. jejuni-negative/anti-GalNAc-GD1a-positive patients, but not in C. jejuni-positive/anti-GalNAc-GD1a-negative and C. jejuni-negative/anti-GalNAc-GD1a-negative patients. Although the anti-GM1-positive/anti-GalNAc-GD1a-negative patients mostly (75%) lacked cranial nerve involvement, distal-dominant weakness (38%) and lack of sensory disturbance (13%) were infrequent. These results may indicate that (1) the combination of C. jejuni infection and anti-GalNAc-GD1a antibodies, but not anti-GalNAc-GD1a, anti-GM1, or C. jejuni infection alone, is associated with a predominantly distal weakness, (2) the presence of anti-GalNAc-GD1a, rather than C. jejuni infection or anti-GM1 antibody, is associated with a lack of sensory disturbance, (3) both anti-GalNAc-GD1a and anti-GM1 antibodies are independently associated with a lack of cranial nerve impairment.