Medulloblastoma, the most common malignant brain tumor of childhood, has a variable prognosis. Although half of the children and young adults with the disease survive longer than 10 years after diagnosis, the others relapse and die despite identical therapy. We have examined the expression of neurotrophins and their receptors in medulloblastoma samples snap frozen in the operating room to preserve RNA integrity. All tumors (n = 12) were found to express mRNA encoding neurotrophin 3 and its receptor TrkC. The level of trkC expression was highly variable, with a more than 50-fold difference between the highest and lowest values. By Kaplan-Meier analysis, patients with tumors expressing high levels of trkC mRNA had significantly longer intervals without disease progression than those with low levels (log-rank, P = 0.03) and a more favorable overall survival (log-rank, P = 0.05). Thus, trkC expression is a prognostic indicator for patients with medulloblastoma.