Hypertrophic olivary degeneration (HOD) is regarded as a secondary degenerative change subsequent to the formation of lesions in the "Guillain-Mollaret Triangle," and this is the result of the loss of transsynaptic neurologic input to the inferior olivary nucleus. HOD usually occurs unilaterally, but bilateral hypertrophic olivary degeneration is known to be rare. We experienced one case of this lesion, and we report here on the bilateral HOD that was secondary to infarction of the brainstem and cerebellum.