The effect of severe trauma on handedness was studied through patient responses from 146 questionnaires that were correlated with individual chart review. Subjects were asked to designate their hand use preference, before and after injury, when performing 16 activities. The incidence of change in hand use was determined within four diagnostic types and five designated anatomical levels of injury. Results indicated a significant difference in the way subjects in different diagnostic types and anatomical levels of injury performed. Simple, short activities that did not require sustained fine motor coordination were reported as being performed more easily with a different hand after injury than complex, continuous activities that required sustained fine motor coordination. Significant differences in job duties and place of employment were found for the anatomical level of an injury but not for diagnostic type. Findings suggest that the diagnostic type, the anatomical level of an injury, and the complexity of a task should be considered before changes in hand use are recommended.