BACKGROUND Glial neoplasms can infiltrate the central nervous system extensively with relative preservation of the underlying neuronal architecture. The differential diagnosis between cerebral glioma and infective lesions can be very difficult to distinguish by MRI only. METHODS We report a 7 year old boy with recurrent vomiting, fever, weakness, abdominal pain and diarrhea. Besides an expressive speech disturbance the neurological examination showed no pathological findings. The sonography revealed discrete hepatomegaly and small pericardial effusion. MRI showed a diffuse mesencephalic and pontine swelling without contrast medium enhancement possibly pointing to an infective lesion. Microbiological, serological and metabolic investigations of blood and CSF were normal. After initial improvement associated with antibiotic, antiviral and dexamethasone treatment the process relapsed progessively. The 1H-MR-spectroscopy showed elevated cholin and decreased N-acetyl-aspartate levels suspicious for a proliferating process. Brain biopsy revealed anaplastic astrocytoma (WHO III). Despite of radiation and chemotherapy the tumordisease deteriorated and the patient died because of progressive brainstem infiltration one year later. CONCLUSIONS This case report shows that cerebral glioma can mimick infective brain disease and that MR-spectroscopy is an important non-invasive tool in this differential diagnosis.