Objective To explore the efficacy of microvascular decompression (MVD)on trigeminal neuralgia and the anatomical characteristics of the responsible blood vessels.Methods The clinical data of 25patients with idiopathic trigemine neuralgia(ITN) undergoing MVD were analyzed retrospectively.The origins of the responsible blood vessels and sites of compression at the trigeminal root were observed and determined.Meanwhile,the anatomical characteristics of the responsible blood vessels and the efficacy of MVD were investigated.Results The offending vessels which were responsible for ITN were identified at root exit zone (REZ) in 21 cases (84％).The most common responsible vessel was the superior cerebellar artery in 13 cases (52％),followed by anterior inferior cerebellar artery in 6 cases (24％).Seventy six percent of the offending vessels were arteries and 8％ were rock vein.No vascular compression but evident increase in the thickness of arachnoid mater covered by the trigeminal nerve was observed in 4 cases ( 16％ ).All patients were relieved for the acute pain and the overall cure rate was 96％.Conclusion MVD is a safe,microinvasive and effective surgical modality for ITN.The key for better outcomes and less complications of MVD is to improve microsurgical techniques and deal with all the involved vessels.