Guillain-Barré syndrome (GBS) sometimes is preceded by cytomegalovirus (CMV) infection. Irie et al. (J. Neuroimmunol. 1996;68:19-26) reported that three patients with GBS subsequent to CMV infection had IgM and IgG anti-GM2 antibodies. In our larger study, the IgMs from the CMV-associated GBS patients showed significantly higher anti-GM2 antibody titers than anti-GM3, anti-GD1a, anti-GD1b, anti-GD2, anti-GD3, anti-GT1b, anti-GQ1b, and anti-SGPG antibody titers. None of the anti-glycosphingolipid antibody titers differed significantly from the others in the IgGs from the CMV-associated GBS patients. However, IgM anti-GM2 antibody frequently was present in GBS patients who were not preceded by CMV infection and non-GBS patients with acute CMV infection. Our results did not support the conclusion of Irie et al. that anti-GM2 antibodies were closely associated with acute CMV infection in GBS, but acute CMV infection, with and without GBS, was associated with IgM anti-GM2 antibody.