Delirium is presumed to be the same syndrome in all ages. Comparing pediatric and adult studies, the authors found many of the same symptoms reported, but often at significantly different rates. Sleep-wake disturbance, fluctuating symptoms, impaired attention, irritability, agitation, affective lability, and confusion were more often noted in children; impaired memory, depressed mood, speech disturbance, delusions, and paranoia, more often in adults; impaired alertness, apathy, anxiety, disorientation, and hallucination occurrence were similar. These may represent true differences in the presentation of delirium across the life-cycle, or may be attributable to inconsistent methodologies. Prospective studies are needed to resolve this question.