Lymphomatoid granulomatosis (LYG) is an angiocentric, angiodestructive lymphoreticular proliferative disease that usually affects the lungs but it has been speculated to also effect the central nervous system (CNS). However, unique primary LYG of the CNS has rarely been reported in the literature. Herein, we describe a clinical case of a 37-year-old female patient with grade 1 primary CNS-LYG having a good prognosis owing to corticosteroid treatment. The aforesaid patient, presented with a headache and left leg weakness with no evidence of a systemic disease. MRI revealed multiple small enhancing nodules in the right hemisphere with diffuse high-intensity lesions on T₂/ FLAIR image. A brain biopsy showed lymphohistiocytic cells with blood vessels infiltrated with CD3+ and CD20+. The Epstein-Barr virus encoded small RNA-ISH test was negative. Based on the above findings, grade 1 primary CNS-LYG was diagnosed. Following the administration of oral corticosteroids, a systemic high-dose corticosteroid therapy was administrated. Complete remission was achieved and maintained for 24 months following treatment. Grade 1 primary CNS-LYG is a rare disease that is not apparently associated with the Epstein-Barr virus (EBV) and possibly yields much better prognosis than the frequently EBV-positive systemic LYG with CNS localization. (Received November 5, 2019; Accepted November 20, 2019; Published February 1, 2020).