Objective  The purpose of the study was to investigate the significance of the changes in lymphocyte subsets of peripheral blood in patients with Guillain  Barre syndrome(GBS).Methods  Blood samples from 15 patients with GBS were studied with flow cytometry to define circulating lymphocyte populations and compared with those from 15 healthy controls.Results  In the GBS patient group,little changes have taken place in the numbers of CD  4  +, CD  3  + and CD    19    +,the percentage of CD  8  + is lower and CD  4  +/CD  8  + is higher than those in normal control group (  P  <0.01).Conclusion  An abnormal immune response is thought to be involved in pathomechanism of GBS and the abnormality of the CD  4  +/CD  8  + value may be a mark of GBS.