Objective To study the diagnostic value of functional magnetic resonance imaging (fMRI) on predicting consciousness in patients with complete locked-in syndrome (LIS).Methods The first patient was diagnosed as uncomplete US,and the second one was diagnosed as Vegetative state,both of them were checked by fMRI.their brains activities in related areas were analyzed when them were called by their consorts and were asked to raise their left hands.Results The primary and secondary auditory cortices of two patients were activated through fMRI while the consort called their names.In raising left hand task,the primary and secondary auditory cortices were activated,and the motor cortex (primary motor area and supplementary motor area) were also activated.The second patient has consciousness and should be diagnosed for complete LIS,but he was misdiagnosed as vegetable state.Conclusion fMRI can be used as an effective method to distinguish LIS from vegetative state.