The Internet is now the single largest source of health information and is used by many patients and their families who are affected by childhood brain tumors. To assess the quality of pediatric neuro-oncology information on the Internet, we used search engines to look for information on five common tumor types (brain stem glioma, craniopharyngioma, ependymoma, low-grade glioma, and medulloblastoma). The Web sites were evaluated for content quality by using the validated DISCERN rating instrument. Breadth of content and its accuracy were also scored by a checklist tool. Readability statistics were computed on the highest-rated sites. Of 114 evaluated Web sites, the sources were as follows: institutional, 46%; commercial, 35%; charitable, 15%; support group, 2%; and alternative medicine, 2%. Good interobserver correlation was found for both ratings instruments. The DISCERN tool rated Web sites as excellent (4%), good (7%), fair (29%), poor (39%), or very poor (21%). Only 5% of the Web sites provided one or more inaccurate pieces of information. Web sites were found deficient in topics covering etiology, late effects, prognosis, and treatment choices. Few sites offered information in languages other than English, and readability statistics showed an average required reading level of U.S. grade 12+ (the suggested level being grades 6-8 for an adult audience). The Internet is increasingly being used as a source of oncology information for patients and their families. Health care professionals should be actively involved in developing high-quality information for use in the next generation of Web sites.