BACKGROUND: Vagus nerve widely innervates in the human body, and it has diverse physiological functions. Many new physiological functions are gradually found. Studies on its action mechanism have been gradually deepened. Vagus nerve stimulation (VNS) has been used for treatment of epilepsy and depression in clinic. OBJECTIVE: To retrospectively investigate the therapeutic effects and mechanism of VNS. RETRIEVE STRATEGY: A computer-based online research in Pubmed with the key words of "vagus nerve stimulation" published between February 1990 and October 2006 in English were systemically reviewed. Totally 583 articles were collected and primarily selected. Inclusive criteria: the mechanism of therapeutic effects of VNS-related literatures. Exclusive criteria: repetitive study. LITERATURE EVALUATION: According to inclusive criteria, of the 57 articles, which met the inclusive criteria, 42 were associated with the therapeutic function of VNS, and 15 with the mechanism of these related functions. DATA SYNTHESIS: Vagus nerve has special nerve innervation and wide projection with extensive physiological effects. Till now, VNS has been used in the therapy of epilepsy and depression, and exact clinical effects have been obtained. Further studies have discovered other functions of VNS, such as the effect on the memory powcr, cognition, and perception to pain. Thus, the studies about VNS become diverse. Just because of the special physiological functions of vagus nerve, VNS can bring some adverse reactions such as foreign body sensation, hoarseness, trigeminal neuralgia, etc. The mechanism of therapeutic function of VNS is still under exploration. CONCLUSION: As a mature surgical technique, VNS has been widely used in the therapy of epilepsy, depression, inflammation, analgesia, relieving itching, etc. Although the mechanism is still unclear, it brings obvious clinical effects.