We treated a 62-year-old woman who developed a dramatic change in personality and behavior following a discrete left-sided medial thalamic infarction involving the dorsomedial nucleus. Neuropsychological testing demonstrated severe impairment of complex executive behaviors that are usually associated with frontal lobe function. Electroencephalography and single-photon emission computed tomography strongly implicated dysfunction of the ipsilateral frontal lobe. This case further supports a functional and physiologic thalamofrontal linkage as part of a broader cerebral network modulating complex human behavior.