Objective To research into the minimal invasive technique and significance of endoscope assisted operation of microvascular decompression via retrosigmoid approach for subjective tinnitus induced by microvascular comprssion syndrome on patients diagnosed by MRI lamella-scan preoperatively.Methods 3 patients underwent the microvascular decompression via retrosigmoid approach with endoscope assisting during operation.After mobilization and elevation of the vein,Teflon felt was placed between the mobilized vessels and vestibulocochlear nerve complex under endoscopy.Introperative ABR and the facial nerve integrity monitoring were performed.All of patients were examined of pure tone auditory test,ABR test,EcochG,vestibular function(electronystagmography),facial nerve function,and observed of clinical situation(including complications and equilibrium function and so on) before and after operation.Results All 3 patients felt tinnitus disappearring 3 to 6 months after operation.Before operation,2 patients’ frequency of tinnitus were 2 kHz to 4 kHz,and sound-volume were 2.5 dB to 3.75 dB beyond average hearing threshold,and another patient’s tinnitus could objectively be measured.Compared with preoperation,postoperative average hearing threshold and facial nerve function had no any remarkable difference,the latent period of Ⅰ-Ⅴ wave were prominently shortened,and no complications occurred.The predominance deflected to the diseased-side was found in one patient and it subsidised after surgery.Conclusion MRI lamella-scan at cerebellopontine angle and internal auditory canal is a method of exactly diagnosing tinnitus induced by microvascular compression syndrome.These patients could effectually treated with microvascular decompression.During endoscopic assisted operration is a safe and a minimal invasive technique,which doesn’t bring about any complication and prolongation of operating-time.