Within two and a half years 82 magnetic resonance imaging and 155 ultrasound examinations were performed in 46 children after treatment for brain tumors. In 42 cases the primary tumors were located in the posterior cranial fossa. Magnetic resonance imaging required sedation in 14 and anesthesia in 3 children. In 6 cases ultrasound was insufficient due to partial closure of the calvarian defect. In the remaining cases ultrasound was falsely negative in two cases, and falsely positive in one case. Magnetic resonance imaging was falsely negative in one case. Sequelae of chemo- and radiotherapy were only depicted by magnetic resonance imaging. For follow-up of tumors of the posterior cranial fossa after surgical treatment ultrasound is the method of choice.