During the first few hours after onset, stroke symptoms may evolve rapidly. We studied the correlation between brain perfusion and aphasia changes during the hyperacute phase of stroke using a new technique of perfusion computed tomography (P-CT). Using an aphasia score developed for each language modality, language was evaluated within 6 hours after onset, then sequentially during the first week. Maps of the penumbra and infarct obtained from P-CT images and definite infarct size evaluated using T2 and diffusion-weighted MRI (DWI) on day 3 were rated by a neuroradiologist, blinded to the clinical deficit. Within 6 hours, deficits in all language modalities were present in 13 out of 24 consecutive patients, corresponding to large anterior-posterior perfusion deficits of the left middle cerebral artery (MCA) territory. The aphasia score correlated with a corresponding perfusion deficit in specific areas of the MCA territory, and showed significantly less improvement when the penumbra evolved toward infarction than when at least part of the penumbra was rescued. Our findings suggest a particularly good correlation between the evolution of aphasic symptoms and penumbra dynamics. Further studies on the relevance of penumbra dynamics in function-specific brain areas to decision taking in hyperacute stroke management are required.