Toxoplasmosis is the most frequent opportunistic infection of the central nervous system among individuals with the acquired immunodeficiency syndrome. Radiographic modalities include brain CT, MRI and PET scan. The differential diagnosis are usually: primary CNS lymphoma, cerebral metastasis, Progressive multifocal leukoencephalopathy, cytomegalovirus. It indicates severe immunodeficiency and, if it remains untreated, it may lead to death.A 65 year old immunodeficiency woman with a Non Hodgkin Lymphoma treated with Chemotherapy. She had been suffering from vomiting, headache and vertigo. Treatment she received Dafalgan, Betaserc, neupogen and nexiam.This case illustrates that a brain biopsy is compulsory before starting any treatment.