Abstract The anterior inferior cerebellar artery (AICA) arises from the lower side of the basilar artery and supplies blood to the rostral olfactory bulb, rostral pontine base, and cerebellar regions. The AICA syndrome was first defined by Adams in 1943. Here, we present a case of a patient with a left AICA occlusion who suddenly started experiencing dizziness and had abnormal gait; he was subsequently diagnosed with ischemia in the left cerebellar hemisphere. A 55-year-old man was admitted to the hospital with complaints of sudden onset of vertigo, speech disorder, and imbalance. The neurological examination revealed gait disturbance, and left-sided ataxia. In addition, dysarthric speech left peripheral facial paralysis, loss of pain and heat sensations in the left half of the face and right half of the body. Bilateral horizontal nystagmus was observed. Babinski and Hoffman signs were also observed on the left side. The patient was evaluated with diffusion weighted (DW) magnetic resonance (MR) imaging. On DW image and apparent diffusion coefficient (ADC) maps precisely determined diffusion restrictions in the antero-inferior part of the left cerebellar hemisphere and the left part of the inferior vermis. MR angiography revealed occlusions in the right internal carotid artery and left AICA; hence, he was administered antiagregan treatment. We have presented this case because infarctions in the AICA have different clinical features from those observed in other cerebellar arteries, and such cases are rarely observed in neurological practice.