Cerebral toxoplasmosis is a rare but often life-threatening infection after hematopoietic stem cell transplantation (HSCT). In such cases, early diagnosis and initiation of treatment are vital. We describe a case of cerebral toxoplasmosis in a patient who underwent HSCT for acute myeloid leukemia. Infection was diagnosed with polymerase chain reaction (PCR) test of cerebrospinal fluid and cranial magnetic resonance imaging scan. The patient treated with trimethoprim-sulfamethoxazole and clindamycin combination. However, she died from nosocomial infection after 15 days of treatment. This life-threatening infection should be considered in a patient who is post-HSCT present with neurologic symptoms and brain lesions. PCR is an important and rapid diagnostic tool for toxoplasmosis. Cranial imaging scan and PCR should be used together to diagnosed.