The diagnosis of cerebral toxoplasmosis in an immunosuppressed patient is based on computer tomography (CT) findings and response to specific empiric treatment. Although infrequent, cerebral toxoplasmosis has been described in patients undergoing bone marrow transplantation (BMT) with lesions compatible with this diagnosis always being found on cranial CT. The case of a patient with Burkitt's lymphoma who received BMT and developed convulsive crisis with repeatedly normal cranial CT scans during the course of severe immunosuppression (graft versus host disease and treatment with 3 immunosuppressive drugs) is presented. Post mortem study demonstrated cerebral cysts of Toxoplasma gondii with slight perilesional inflammatory infiltrate. Normal CT in patients with neurologic foci and severe immunosuppression following BMT does not exclude the diagnosis of cerebral toxoplasmosis, therefore more sensitive diagnostic techniques should be performed, particularly in areas in which infection by toxoplasma is endemic.