The answer to this question depends on the severity of the accident. If the injury is minor, then it is not necessary to go to a doctor. However, if you have a headache, neck pain, or any open wounds, then you should go to the hospital for an evaluation.
If you have been in a serious accident, then it is recommended that you go to the hospital immediately. You may feel fine at first, but it can a few days or even weeks for symptoms of brain injuries and internal injuries to show up.