Objective To determine the evaluation day that evoked potentials (EPs) best correlates with wakening outcome for comatose patients; to determine whether middle latency somatosensory evoked potential (MLSEP) combined with event-related potential (ERP) improved the prediction of awakening. Methods The prospective cohort study included 113 comatose patients in neuro-intensive care unit, whose etiologies of coma were stroke, hypoxic-ischemic encephalopathy, intracranial infection and others. We recorded MLSEP and ERP for all comatose patients at 7, 14, and 30 day after coma onset, respectively. According to the Glasgow Outcome Scale followed after 3 month, patients were classified as awakening (GOS 3–5) or non-awakening (GOS 1–2). Results The present/absent classification of N60, N100 and MMN were statistically different (P Discussion According to the AU-ROCs analysis, EPs at 7 day after coma are early indicator for awakening outcome. And N60 is a stable, reliable, and permanent parameter in predicting awakening. However, the AU-ROC of MMN showed an obviously declining tendency. And further analysis revealed that specificity of MMN was still above 85%, but its sensitivity dropped significantly.That is the occurrence of MMN will reduce with time postponed. After the combination of N60 and MMN, the accuracy for prediction was improved with increased sensitivity and specificity, superior to each single indicator applied separately. Conclusion MMN and MLSEP are strongest prognostic factors for awakening outcome. And at 7 day after coma onset, the combination of MMN and MLSEP improved the predictive performance for awakening. Significance This study first confirmed that 7 day after coma onset can be used for predicting awakening outcome, and showed that the accuracy of MMN declined as the evaluation of EPs delayed.