['It has been suggested that out-of-hospital bispectral (BIS) index monitoring during advanced cardiac life support (ACLS) might provide an indication of cerebral resuscitation. The aims of our study were to establish whether BIS values during ACLS might predict return to spontaneous circulation, and whether BIS values on hospital admission might predict survival.', 'This was a prospective observational study in 92 patients with cardiac arrest who received basic life support from a fire-fighter squad and ACLS on arrival of an emergency medical team on the scene. BIS values, electromyographic activity, and signal quality index were recorded throughout resuscitation and out-of-hospital management.', 'Seven patients had recovered spontaneous cardiac activity by the time the medical team arrived on scene. Of the 92 patients, 62 patients died on scene and 30 patients returned to spontaneous cardiac activity and were admitted to hospital. The correlation between BIS values and end-tidal CO(2) during the first minutes of ACLS was poor (r(2)=0.02, P=0.19). Of the 30 admitted patients, 27 died. Three were discharged with no disabilities. There was no significant difference in BIS values on admission between the group of patients who died and the group who survived (P=0.78).'] Is bispectral index monitoring useless during cardiac arrest patients ' resuscitation?