In urethane anaesthetized rabbits, reflex contraction of the inferior oblique muscle of a unilateral rye was evoked by the stimulation of a relevant vestibular canal nerve. Eye movement evoked by the inferior oblique muscle contracion was carefully observed with naked eyes, and recorded by means of the electrooculographic and electronystagmographic methods. The following results were obtained. 1) Contraction of the inferior oblique muscle evoked by a canal nerve excitation produced excycloduction of the eyeball associated with depression (downward rotation) instead of elevation. 2) Such depression of the eyeball was demonstrated even after the resection of the inferior oblique muscle. These experimental evidences indicate that tile rotatory action (secondary action of the muscle) of the inferior oblique muscle in the rabbits is apparently different in its direction from those already reported in the binocular animals such as cat, dog and monkey.