BACKGROUND–To correlate the serum tumor necrosis factor-&agr; (TNF&agr;) concentrations before, during and following plasma exchange in patients with Guillain-Barré syndrome (GBS). In this prospective study, 21 GBS patients were selected. Patients in clinical stages III to V were subjected to plasma exchange. The control group included equal numbers of age-matched patients with other neurological diseases and healthy voluntary blood donors. A sandwich ELISA method was applied to estimate serum TNF&agr; concentrations in test and control groups.REVIEW SUMMARY–Twelve GBS patients had elevated serum TNF&agr; levels that ranged between 74 and 182 pg/mL. All 12 GBS patients showed a steady decrease in the TNF&agr; concentration following plasma exchange and also showed a positive correlation with neurological recovery.CONCLUSIONS–We conclude that serum TNF&agr; concentrations are elevated in 57.1% of GBS patients and TNF&agr; level decreases following plasma exchange.