To study the occurrence and incidence of various electroencephalographic patterns, the electroencephalograms of unresponsive pediatric patients admitted to the intensive care unit were analyzed. The interpreters were unaware of the patients’ clinical diagnoses. A total of 178 electroencephalographic studies performed on unresponsive patients were analyzed over a period of 3 years. The mean age of the study patients was 7.9 years. Sixty-six patients were less than 1 year old. The following electroencephalographic patterns were observed: 58 patients (33%) manifested electroencephalographic patterns consistent with nonconvulsive status epilepticus. Of the patients with nonconvulsive status epilepticus, 32 patients (18%) had generalized nonconvulsive status epilepticus and 26 patients (14%) manifested partial nonconvulsive status epilepticus. The remaining 120 patients (67%) manifested diffuse cerebral dysfunction, with the majority having severe diffuse cerebral dysfunction. Only 4 patients (2%) had triphasic waves, suggesting a metabolic encephalopathy. Thirty-six percent of the patients under the age of 1 year had electroencephalographic patterns consistent with nonconvulsive status epilepticus. Nonconvulsive status epilepticus is a relatively common electroencephalographic pattern in unresponsive pediatric patients. Metabolic encephalopathy is uncommon in this patient group.