Concurrence of medulloblastoma and Chiari deformity (type-1) in a pediatric patient is extremely rarely seen. 10 years old girl. She had first complained of nausea, abdominal pain, and vomiting. She had a mild headache for three days. Computed tomography was taken. There were sequelae related to her previous illness and noticed the appearance of the left cerebellar tonsils down to the foramen magnum level and mild prominence in the third ventricle. Cranial imaging was performed with magnetic resonance imaging. There was a lesion as a solid mass, about 60 mm sized in the level right cerebellar, a cerebellar tonsil hernia (11 mm), and ventricular dilatation in magnetic resonance imaging. Histologically, the lesion was a classic type of medulloblastoma. The coexistence of two diseases may occur in the same patient. Magnetic resonance imaging, which indicates the craniovertebral junction can be used singly.Because MRG is the first method to be selected for diagnosis.