Objective To study the clinical, imaging and pathological features of primary angiitis of the central nervous system (PACNS).Methods We collected 5 cases with PACNS in Navy General Hospital from 2008 to 2011, stereotactic brain biopsy was taken in 4 cases and craniotomy in 1 case.We retrospectively analyzed the clinical, imaging and pathological characteristics of the 5 PACNS cases.Results The cases presented with headache, seizures, blurred vision, speech disorder and focal neurological deficits.Brain images showed supratentorial lesions in 4 cases, and both supra-and infratentorial lesions in 1 case.All the cerebral lobes were involved.The lesions were unilateral in 3 cases, and bilateral 2 cases.The lesions had blurred boundaries, involved gray matter, with various degrees of gyrus-like and patchy enhancement.Pathological features were that a large number of lymphocyte infiltration around small vessels in cortical and white matter, with T lymphocytes predominance.There were necrosis, phagocytes, proliferated astrocytes and pronounced hyperplasia small vessels.Fibrinoid necrosis was seen in vessel walls in three cases.Treatments with glucocorticoid and immunosuppressive agents were satisfied.Conclusions The main clinical manifestation of PACNS was focal neurological deficit.The lesions were mainly multiple and unilateral, located in supratentorium.Diagnosis need to be combined with clinical manifestations, laboratory, imaging and pathological examinations.