The authors present the case of a child aged 7 years who suffered from relapsing acute lymphocytic leukemia. Treatment consisting mainly of oral and intrathecal methotrexate and x-ray therapy produced remission of the hematologic symptoms. Three years after the onset of the leukemia, mental deterioration gradually appeared. Radiography of the skull revealed diffuse bilateral calcium deposits in both cerebral and cerebellar hemispheres. Four years after the onset of the disease, a hematologic relapse occurred. Behavioral disorders became more severe and the child died after a period of seizures and unconsciousness. The main pathologic data obtained by the study of a brain biopsy and after a complete postmortem examination consisted of calcifications located bilaterally in the cerebral and cerebellar cortex. No signs of leukemia were present. Cerebral calcification is an extremely rare complication in the course of the therapy of lymphocytic leukemia. Its possible causes are discussed.