We report our findings in a case of ophthalmoplegia caused by a transorbital penetrating brainstem injury. An 8-year-old boy was accidentally injured by a broken fishing fiberglass pole which penetrated through the right orbit and entered the brainstem. Magnetic resonance imaging showed a linear wound that entered and passed through the pons obliquely and reached the fourth cerebral ventricle and cerebellar vermis. He had a left-sided hemiplegia and left facial nerve palsy and was diagnosed with "one-and-a-half syndrome". His hemiplegia and left facial nerve palsy resolved in 2 weeks leaving only a left abducens nerve palsy. The eye position and eye movements fully recovered within 3 months. These findings suggest a good prognosis for this type of trauma unless life-threatening changes develop.