Objective: To determine the benefits of additional therapy specifically directed at the hand in people with acquired brain impairment. Design: An assessor-blinded randomized controlled trial. Setting: Rehabilitation hospital. Participants: A sample of 39 adults with hand impairment following stroke (90%) or traumatic brain injury (10%). The median (interquartile) time since injury was 1.6 months (0.5-3.5 months). Intervention: The experimental group (n = 20) received an additional one-hour session of task-specific motor training for the hand five times a week over a six-week period. The training was administered on a one-to-one basis. The control group (n = 19) received standard care which consisted of 10 minutes of hand therapy three times a week. Both groups continued to receive therapy directed at the shoulder and elbow. Outcome measures: Primary outcomes were the Action Research Arm and Summed Manual Muscle Tests measured at the beginning and end of the six-week period. Results: The mean (SD) Action Research Arm Test valuesfor experimental participants improved from the beginning to the end of study from 10 points (15) to 21 points (23) and the equivalent values for the Summed Manual Muscle Test improved from 35% (33) to 49% (35). There were similar improvements in control participants. The mean between-group differences for the Action Research Arm and Summed Manual Muscle Tests were -6 points (95% confidence interval (CI), -20 to 8) and 3% (95% CI, -10 to 16), respectively. Conclusion: Hand and overall arm function of all participants improved over the six-week period, however there was not a clear benefit from providing additional hand therapy.