PURPOSE: To report a case of recurrent binocular, vertical diplopia presenting as an isolated, unilateral inferior rectus paresis occurring in a patient with a mesencephalic tegmental cavernous angioma. METHOD: Case report. A 30-year-old man with recurrent vertical diplopia underwent neuro- ophthalmic examination, laboratory examination, pharmacologic testing, and magnetic resonance imaging and angiography. RESULTS: Magnetic resonance imaging disclosed a lesion in the mesencephalon consistent with a cavernous angioma. Magnetic resonance angiography was negative. CONCLUSIONS: Isolated inferior rectus paresis is a rare phenomenon. This unique case involved a patient with recurrent inferior rectus paresis secondary to a mesencephalic cavernous angioma. The disparity between the extent of the lesion and the neuro-ophthalmologic consequences is remarkable.