The aim of the study is to investigate whether the disorders of calculation observed in patients with Broca's aphasia are due to linguistic factors whereas those observed in patients with Wernicke's aphasia may be reduced in part to a disorder in the ability of spatial visualization. Two sets of arithmetic tasks were given to 20 Broca's aphasics, 20 Wernicke's aphasics, 20 patients with right hemispheric retrorolandic cerebral lesions and 40 patients with no brain damage. The solution of the tasks required different degrees of spatial visualization. The statistical evaluation of the data showed, as hypothesized, that Wernicke's aphasics perform significantly poorer than Broca's aphasics in tasks with a more pronounced spatial component than in the tasks having a predominantly verbal component.