Two patients with unilateral olivary hypertrophy (OH) following a pontine tegmental hematoma are presented. Both showed palatal myoclonus and one patient showed an extremity myorhythmia on the opposite side of OH. The magnetic resonance (MR) examination demonstrated an abnormal unilateral hyperintense lesion in the ventral part of medulla oblongata on T2-weighted images. The MR findings were highly suggestive of the pathological nature of the lesion, showing the value of MR.