Critically ill patients are at high risk of non-convulsive status epilepticus (NCSE). As clinical signs of NCSE are subtle and unspecific, EEG is necessary to make the diagnosis. This is a review of the terminology for EEG reporting and the criteria for NCSE in critically ill patients. We discuss the newly proposed ictal-interictal continuum, and how caution is needed when assessing EEG criteria in order to avoid both over- and undertreatment. Finally, we discuss how specific EEG findings, in combination with clinical information, can help infer treatment decision and need for continuous EEG monitoring.