The evidence concerning the neurophysiological organization of language can be obtained only indirectly, with one of the most important sources being aphasia. In this paper, the authoress presents some results from her long-term neurolinguistic research. First, she surveys the manifestation of aphasia in different languages and offer a linguistic interpretation of these data. She argues that it is the typological character of the language which influences the symptoms. Her cross-linguistic study showed that the decisive factors for evaluating aphasia in a language are: (a) the number of grammatical words; (b) the way in which grammatical morphemes are connected to the stem; (c) the extent of paradigms. The authoress then focuses on the grammatical errors in the spontaneous speech of Czech aphasics and discuss: (1) the distribution of errors among grammatical categories; (2) the hierarchy of forms within each category. Finally, she presents a synthesis of the morpho-syntactic aphasic symptoms in Czech. The aim of her work is not only to describe aphasia, but also to shed some light on the functioning of language under aggravated conditions.