BACKGROUND: Backrest positioning for brain-injured adults is variable. Some data support using a flat backrest to optimize cerebral perfusion pressure; other data support elevating the head of the bed at least 30 degrees to reduce intracranial pressure. OBJECTIVE: To determine whether a flat backrest position or a backrest elevation of 30 degrees provides both optimal cerebral perfusion pressure and optimal intracranial pressure in adults with brain injuries. METHODS: A randomized crossover experimental design was used to collect data on 8 adults 18 to 45 years old who had nonvascular, closed-head, traumatic brain injury. Repeated-measures multivariate analysis of variance was used to analyze the data. RESULTS: Overall, compared with use of a flat/horizontal position, use of a backrest elevation of 30 degrees resulted in significant and clinically important improvements in both intracranial and cerebral perfusion pressures. None of the subjects experienced adverse clinical changes in either intracranial pressure or cerebral perfusion pressure with either backrest position. CONCLUSION: The results strengthen the research foundation for raising the backrest position for adults, 18 to 45 years old, who have nonvascular, nonpenetrating, severe brain injuries.