Recently it was found that plasmapheresis and intravenous immunoglobulins are effective in treating patients with Guillain-Barré syndrome (GBS). However, these treatments are expensive and not without possible adverse effects. Because signs and symptoms predictive for respiratory failure in GBS would be helpful in targeting the treatment, risk factors for respiratory failure were evaluated in 120 children with GBS. Twenty children required assisted ventilation. None of the children without any of the following risk factors had respiratory failure. If the symptoms of GBS began within 8 days after a preceding infection, the odds ratio (OR) for respiratory failure was 4.9 [95% confidence intervals (CI): 1.3-18.5]. Cranial nerve involvement was more common in children who required assisted ventilation (15/20 versus 32/100, OR: 6.4, 95% CI: 2.1-19.1). A cerebrospinal protein level > 800 mg/L during the first week had an OR for assisted ventilation of 3.1 (95% CI of OR: 1.04-9.0). In the logistic multivariate model, all of these risk factors were associated with the need for assisted ventilation. On the basis of our findings, preventive treatment with either plasmapheresis or intravenous immunoglobulins could be directed to those children with any of the risk factors; for those patients without the risk factors, clinical monitoring would be satisfactory.