Central nervous system infection is one of the most serious infections inpediatric cancer patients. The organisms depend on the type of the immune system affected; initial diagnosis of these patients depends mainly on the type of immune defect, the manisfestations and the type of the clinical syndrome. While specific diagnosis needs neuroradiographic and laboratory data with special concern to the opportunistic infection. Early initiation of empirical therapy is of utmost important in managing cancer patients with central nervous system infection to avoid the high mortality and sever sequelae associated with delayed treatment.