Recent data have suggested that patients with both a normal cranial CT scan and normal neurologic examination following minimal head injury (MHI) have no risk of neurologic deterioration. This study prospectively examined the safety of discharging patients from the emergency department (ED) after MHI whether or not there was a responsible observer at home. MHI was defined as a history of loss of consciousness (LOC), a Glasgow Coma Scale (GCS) score of 14 or 15, and no focal neurologic findings. In a 4-month period 111 patients with MHI were evaluated. Fifteen (14%) patients had a CT scan which revealed an intracerebral injury; 96 patients had a normal CT scan; five patients with normal CT scans were admitted because of persistent lethargy; and one patient was admitted after his CT that demonstrated an old infarct; the remaining 90 patients were discharged. There were 71 men and 19 women with a mean age of 29 years. The mechanism of injury was assault in 55, MVA in 30, and falls in five. The initial GCS in was 15 in 79 and 14 in 11. Fifty-eight per cent of patients were intoxicated. Fifty-seven (63%) patients were successfully contacted by telephone; none had developed any neurologic symptoms. Thirty-one patients who could not be followed up gave fictitious phone numbers. These data suggest that CT can reliably triage patients who can be discharged from the ED following MHI, even in the absence of a responsible observer. Hospital admission can be avoided in more than 80% of patients sustaining MHI, better utilizing scarce hospital resources.