Agitation after traumatic brain injury is disruptive for patient care, distressing, and difficult to treat. The use of propranolol has been advocated to control agitation after brain injury. It reportedly lacks some of the deleterious cognitive and emotional effects of other medications and physical restraints. This study was designed to test if propranolol is effective in reducing agitated behavior. Subjects had traumatic closed-head injury treated at a combined Level I Trauma Center and Rehabilitation Center. Twenty-one subjects met the criteria of agitation and were treated with propranolol or placebo in a double-blind fashion. The intensity of agitation was significantly lower in the treatment group although the number of episodes were similar. The use of restraints was also significantly lower in the treatment group. The results support the effectiveness of propranolol in reducing the intensity of agitation during the initial hospitalization after closed-head injury.