Brain abscess rarely occurs in a patient with hematologic malignancy. Leukemia is the most common hematologic malignancy and can manifest to CNS as cerebrovascular complications, infections, or metastatic brain tumors. Brain abscess in a patient with leukemia has an unspecified presentation, makes challenging diagnosis processes, and contributing to increased mortality and morbidity. We report and describe in detail an unusual case of a 44-year-old man with brain abscess and ALL. Specifically, the patient underwent a series of tests, brain MRI, and MR Spectroscopy. The results of the tests are reported here. We discuss the occurrence, the clinical presentation, and association between these two diagnoses, possible etiopathogenic mechanisms, management, and prognosis of this condition.