In Part I of this article, we present our data collected over the past 8 years on the clinical evaluations of pediatric brain tumors with an emphasis placed on the more common neoplasms. Our data consists of 385 children ranging in age from newborn to 18 years. The majority of children presented with signs of raised intracranial pressure (including nausea, vomiting, and headaches), seizures or other focal neurologic deficits. Five percent of our children presented to outlying hospitals with symptoms that retrospectively turned out to be due to brain neoplasms but were misdiagnosed as "gastroenteritis," "viral upper respiratory tract infection," or even viral meningitis. These delays in diagnosis can cause serious negative outcomes for these patients and can be avoided through more careful neurologic and ophthalmologic examination at the time of first presentation. Central nervous system neoplasms are not uncommon in children and any child presenting with nausea, vomiting, and headaches should raise the suspicion of a primary brain tumor and should receive both a thorough neurologic exam and screening for papilledema. If papilledema is present, these children should be referred for proper neuroradiologic evaluation (which will be addressed in Part II.