To the Editor: Clinical symptom spectrum of paroxysmal noctal hemoglobinuria (PNH) is consisted of chronic intravascular hemolysis, hemoglobinuria, relative bone marrow failure, and the rarity of thrombosis.[1] The neurological complications generated by PNH were almost exclusively a result of cerebral venous thrombosis.[1?3] However, moyamoya syndrome (MMS) secondary to PNH (PNH?MMS) is rarely described in the literature.[2?5] We report herein a case of PNH?MMS to raise the awareness of this disease in PNH patients presenting with acute neurological deficits.