Plasmapheresis has been advocated in the treatment of childhood Guillain-Barré syndrome under the assumption that the results of adult series can be extrapolated to children. To test this assumption, we retrospectively evaluated the medical charts of all children who were admitted to The Children's Hospital of Philadelphia between January 1984 and March 1989, with the diagnosis of Guillain-Barré syndrome. Of the 30 patients identified, 7 were excluded because they had mild disease. Of the remaining 23, 9 underwent plasmapheresis and 14 served as historic control subjects. The two groups were similar with respect to age, presenting symptoms, finding on initial physical examination, and antecedent illnesses at the time of diagnosis. The mean time to recover to Grade 2 (independent ambulation) was significantly shorter in the plasmapheresis-treated group, 24.0 ± 25.4 days, compared to 60.2 ± 43.6 days in control subjects (mean ± 1 SD). Our results indicate that plasmapheresis diminishes morbidity in childhood Guillain-Barré syndrome by shortening the interval until recovery of independent ambulation.