To assess the prognosis of the Guillain-Barre syndrome and identify the main prognostic indicators, 297 patients with Guillain-Barre syndrome recruited through a network of Italian centres were followed up for 24 months or until clinical recovery, whichever was earliest. For each patient the time to plateau, improvement, clinical recovery, or death was calculated, and prognostic indicators (age, sex, antecedent events, disability at admission and nadir electrophysiological patterns) and treatments were noted. The mean duration of follow-up was 309 days. During this period, 212 patients (71%) recovered, 48 (16%) had residua and 33 (11%) died. The mean times to nadir improvement and clinical recovery were 12, 28 and 200 days. Using life-tables and survival curves, the cumulative probability of achieving the plateau of symptoms was 73% by 1 week and 98% by 4 weeks. Improvement started during the first week in 36% of cases and within 4 weeks in 85%. The rates of clinical recovery at 1 and 4 weeks, 6, 12 and 24 months were 4, 24, 57, 70 and 82%, respectively. The chance of recovery was significantly affected by age, antecedent gastroenteritis, disability, electrophysiological signs of axonopathy, latency to nadir and duration of active disease. The main treatments did not seem to affect the chance of recovery.