Right hemiparesis with right-sided pain and ataxia developed in a 68-year-old man. Sensation, neuropsychological function, and somatosensory evoked potentials were normal. Computed tomography showed an isolated fresh infarct in the left part of the thalamus. The pain and ataxic disturbances were related to involvement of the thalamus itself, but the hemiparesis with hyperactive tendon reflexes and Babinski's sign was probably due to associated dysfunction in the adjacent internal capsule from compression or edema. In the available clinicopathological reports of cases with hemiparesis and thalamic infarction, contiguous involvement of the internal capsule or no associated lesion has been reported. Because of the occurrence of pain, which is not present in pontine, mesencephalic, or capsular ataxic hemiparesis, we suggest that the syndrome seen in our patient be called "painful ataxic hemiparesis."