Objective To analyze the therapeutic effects of microvaseular decompression on primary trigeminal neuralgia. Methods The general clinical data,culprit vessels and therapeutic effects of the surgical interventions were analyzed in 181 patients(aged from 24 to 79 years with a mean of54.9 years,including 78 male and 103 female patients)with established diagnosis of primary trigeminal neuralgia admitted from January,2000 to Deceber,2007. Results Blood type O was present in 43.65%of the 181 patients with trigeminal neuralgia,which had an increasing tendency compared to the national norm(33.8%).The morbidity ratio between the right and left side was 1.8:l in these patients.Forty-five patients(24.86%)were identified to have more than 2 culprit vessels.The culprit vessels included the superior cerebellar artery(96 cases),posterior inferior cerebellar artery(7 cases),anterior inferior cerebellar artery(25 cases),arteries communicated with veins(25 cases),internal auditory artery (13 cases),basilar artery(15 cases),vertical artery(9 cases),exclusive veins(15 cases,mainly vena pelrosa and bridging vein)and unknown vessels(9 cases).of the 181 cases,171(94.48%)were cured within one month,9(4.97%)showed relieved symptoms but required drug therapy,and 1 was in vegetative state(0.55%). Conclusions Patients with blood type O may have greater chance of developing primary trigeminal neuralgia.Microvascular decompression is an ideal treatment for primary trigeminal neuralgia,and clear identification of the culprit vessels can be crucial for decreasing the postoperative recurrence.