A 62 year-old male patient presented with isolated oculomotor nerve pa
lsy following a small infarction of the medial ventral midbrain, docum
ented by magnetic resonance imaging. There was a 12-year history of hy
pertension, but no diabetes mellitus. Angiography revealed atheroscler
osis of the paramedian mesencephalic arteries. Magnetic resonance imag
ing may be useful in patients with small brain stem infarctions.