OBJECTIVE: To investigate the usefulness of the somatosensory evoked potentials (SEP) study in predicting the outcome of complete peripheral nerve injury. METHOD: Thirty eight complete peripheral nerve injuries, diagnosed by motor and sensory nerve conduction studies (NCS) and needle electromyography (nEMG), were studied. Nerve injuries were grouped into two groups with and without SEP recorded at the time of initial evaluation. Outcome of nerve injuries was graded from 0 to 3 based on the results of NCSs and nEMG, followed up for more than six months. Grade 0 was designated for those with no evidence of recovery, and grade 3 for those with recovery in nEMG and both motor and sensory NCSs. RESULTS: At the time of initial electrodiagnosis, SEP study showed no response in 25 cases, but SEP could be observed in 13 cases, although they were attenuated or delayed. Recovery of nerve injury was observed in 22 cases, despite the findings compatible with complete injury in initial NCSs and nEMG. The group in which SEPs were recorded showed significantly higher grades of recovery, compared to no response group. CONCLUSION: In predicting the prognosis of complete peripheral nerve injuries, SEP study could be useful as a supplementary electrodiagnostic method.