Background: Brain tumors represent the most common solid neoplasm in children and second most common pediatric malignancy overall.  The majority of primary childhood brain tumors occurs in the infratentorial compartment and includes: medulloblastoma, juvenile pilocytic astrocytoma (JPA), ependymoma, brainstem/pontine glioma, and atypical teratoid rhabdoid tumor (ATRT) which is an additional rare but important primary brain tumor of early childhood. Objective: This study aims to provide an overview of the imaging features and appearances of the most common primary posterior fossa brain tumors in children and the diagnosis of medulloblastoma.   Patients and Methods: The pool of our study was 25 patients (12 males and 13 females) who presented to diagnostic radiology departments at EL Demerdash Teaching Hospital and National Cancer Institute. They had been diagnosed to have posterior fossa lesions. Patients' age ranged from 1 to 17 year with mean age of 4.73 years.Results: statistically significant difference between medulloblastoma and other posterior fossa tumors according to location and diffusion. Medulloblastoma is 4^th ventricular in location and shows restriction in diffusion weighted images. Conclusion: Medulloblastoma is predominately 4^th ventricular in location, Medulloblastoma is restricted in diffusion weighted images.