Out-of-hospital cardiac arrest (OHCA) is associated with significant mortality or may have a poor neurological outcome. Various community-training programmes have improved practices like bystander cardiopulmonary resuscitation (CPR) and early defibrillation using automated external defibrillator (AED). Post-resuscitation care has also changed significantly in the millennium. Interventions like targeted temperature management (TTM), avoidance of hyperoxia and emergency cardiac catheterisation have given patients a chance of a better neurological outcome. Despite these timely interventions, it is still very difficult to predict neurological outcome. The European Resuscitation Council and European Society of Intensive Care Medicine (ERC-ESICM) published guidance in 2015 with a strong recommendation to delay prognostication for at least 72 h and with an emphasis to adapt a multimodal approach, which includes neurological examination, biomarkers, electroencephalogram (EEG) and radiological tests. These interventions not only have cost attached to them, but the unpredictability has a significant emotional impact on family members. Bispectral index (BIS) monitoring device acts on the principle of EEG and converts the waveform into an absolute number and also measures the burst suppression. We hypothesize that patients who have a low BIS value and high burst suppression within 24 h of presentation will have a poor neurological outcome. The primary objective of this review is to look at BIS monitor as a tool, which could help bring forward the timing of prognostication.Electronic databases will be systematically searched for randomised controlled trials and prospective or retrospective cohort studies with no language restrictions. The search will be supplemented with grey literature searches of thesis, dissertations and hand searching of relevant journals. Two independent reviewers will screen, select and perform analysis according to the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) method. The selected studies will be analysed using the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) system. Meta-analysis will be performed if suitable.This review will synthesize the evidence on the use of BIS monitors within 24 h of achieving return of spontaneous circulation (ROSC) and may help in early prognostication.PROSPERO CRD 42016050224 .