The cerebral function monitor (CFM) was used in 26 subjects, deeply comatose for a variety of reasons, in order to determine its value as a proghosticator for survival in this group of patients. Results suggest that it may be useful in predicting outcome in patients who do not regain neurologic competence within 2 h after cardiac arrest and resuscitation. In this group, initial CFM values of 10 μv or above correlated well with survival, and values of 3 μv or below correlated with death.The instrument was not a useful tool in predicting outcome in patients with dynamic primary neurological disorders, although a reduction in the CFM tracing did precede deterioration in clinical neurological function in some.The value of the CFM could not be determined for patients with drug overdosage because of the small size of this group.