The purpose of the study was to assess the safety of physical therapy by investigating its effects on intracranial pressure (ICP) and cerebral perfusion pressure. The subjects were 65 patients in a neurosurgical intensive care unit who had normal ICP (< 15 mm Hg) or increased ICP (> 15 mm Hg). Intraventricular ICP was measured in a 30-degree head-up position (all patients) and in supine and 45-degree head-up positions (patients with normal ICP) during passive range of motion (comatose patients) and exercises involving limb movement (awake patients). In patients with normal ICP, passive range of motion decreased mean ICP by 1 mm Hg in the supine position but not in the head-up position. In patients with high ICP, it decreased ICP by 2 mm Hg. Limb exercises left the mean ICP essentially unchanged in both the patients with normal ICP and the patients with high ICP. Isometric hip adduction increased mean ICP by 4 mm Hg in patients with normal ICP. It did not affect ICP in patients with high ICP. Limb movement was associated with suppression of abnormal ICP waves and improvement of consciousness in 13 patients. Physical therapy can be used safely in patients with normal or increased ICP provided that Valsalva-like maneuvers are avoided. [Brimioulle S, Moraine J-J, Norrenberg D, Kahn RJ. Effects of positioning and exercise on intracranial pressure in a neurosurgical intensive care unit.