The speech disturbance resulting from infarction limited to the Broca area has been delineated; it differs from the speech disorder called Broca aphasia, which results from damage extending far outside the Broca area. Nor does Broca area infarction cause Broca aphasia. The lesions in 20 cases observed since 1972 were documented by autopsy, computerized tomography, or arteriogram; the autopsy records from the Massachusetts General hospital for the past 20 years and the published cases since 1820 were also reviewed. The findings suggest that infarction affecting the Broca area and its immediate environs, even deep into the brain, causes a mutism that is replaced by rapidly improving dyspraxic and effortful articulation, but that no significant distrubance in language function persists. The more complex syndrome traditionally referred to as Broca aphasia, including Broca's original case, is characterized by protracted mutism, verbal stereotypes, and agrammatism. It is associated with a considerably larger infarct which encompasses the operculum, including the Broca area, insula, and adjacent cerebrum, in the territory supplied by the upper division of the left middle cerebral artery.