Brainstem gliomas constitute 10% of brain tumors in children and less than 2% in adults. Since therapeutic options are limited and brainstem gliomas are associated with a high morbidity and mortality, we sought to analyze the prognostic factors associated with a better outcome. We reviewed the records of 86 patients with brainstem gliomas treated between 1996 and 2006. We recorded demographic and clinical variables as well as radiological findings and survival. Patients were divided in two groups regarding overall survival: late progressors (survival ≥ 12 months) or early progressors (survival< 12 months). Of 86 patients with brainstem gliomas, 55.8% were females. The mean age at diagnosis was 14.2 years (range 1 to 52 years). Twenty-four (27.9%) patients were adults. Lesions were located at pons in 75.6% of patients, midbrain in 15.1% and medulla in 9.3%. There was no difference between early and late progressors concerning gender, age at onset, location at pons, presence of necrosis or contrast enhancement observed at MRI or surgical resection. In both univariate and multivariate analysis, only a short duration of symptoms before diagnosis (< 3 months) was associated with a worst prognosis (odds ratio 5.59, 95% CI 1.94 to 16, p = 0.0014). A short duration of symptoms, which may imply a more aggressive tumor, was associated with a worst prognosis in patients with brainstem gliomas. This information may be useful in the selection of patients for future therapeutic trials.