Toxoplasmosis is a rare but fatal complication in hematopoietic stem cell transplant recipients, usually associated with allogeneic hematopoietic stem cell transplantation (HSCT). We report a case of cerebral toxoplasmosis in a patient with multiple myeloma, following tandem autologous stem cell transplantation. A 55-year-old Korean male presented with weakness in both legs that had progressed to both arms. A magnetic resonance imaging scan of the brain revealed multiple, variable-sized ring-enhancing lesions with surrounding edema in the cerebral hemispheres and brain stem. Stereotactic biopsy revealed bradyzoites of Toxoplasma gondii in the brain tissue. The patient received trimethoprim-sulfamethoxazole, followed by pyrimethamine and sulfadiazine, accompanying treatment for progressive multiple myeloma. Cerebral toxoplasmosis should be considered as one of the differential diagnoses in patients with neurologic signs following autologous HSCT.