We report the adaptation of the Aachen Aphasia Test (AAT) to the Portuguese language (PAAT) and the results of its standardization in 125 persons with aphasia and 153 healthy controls. Patients with aphasia had a previous syndromic diagnosis, obtained through a Portuguese aphasia battery, which served as a reference. The control group was stratified by age and educational level. Hierarchical cluster analyses showed good construct validity. The increasing degree of difficulty and complexity throughout the item sets comprising subtests was confirmed. The discriminatory power of the PAAT for the selection of aphasic from non-aphasic persons proved to be as high as for the AAT versions in other languages. Classification of standard aphasic syndromes by means of discriminant analyses was good. Internal consistency, measured by means of Cronbach's alpha coefficient, was high to very high for the different PAAT subtests. Performance differences caused by age or educational level among the healthy control persons emphasized the need for correction factors. In conclusion, the PAAT showed robust psychometrical properties, comparable to the original German and to adaptations to other languages. It constitutes a useful tool for cross-linguistic and multicenter studies. (JINS, 2008, 14, 1046–1056.)