We report a man admitted to inpatient rehabilitation 6 wk after traumatic brain injury, who presented with bilateral knee heterotopic ossification. In addition to conventional physical therapy, we applied a continuous passive motion device during 4 wk increasing the range of motion of the knees. On the basis of the limited current literature and this case, we suggest that the use of continuous passive motion devices for heterotopic ossification may be effective and safe and should be the subject of further study.