We report a patient (FBI) in whom a category specific deep dyslexia was demonstrated. The patient was globally dysphasic with dyslexia and dysgraphia, and his dyslexic syndrome was characterised by a dramatic loss of phonological processing together with a partial loss of whole word reading. In the context of an overall poor level of reading accuracy, concrete words were read better than abstract words. Within this concrete word vocabulary, living items were read more accurately that non-living items. Perhaps most strikingly, he also had a remarkably preserved written proper noun vocabulary. A series of experiments explored the relationship between FBI's comprehension of the spoken and written word, and in each a significant category-by-modality interaction was demonstrated. His comprehension of the written word was impaired significantly more than his comprehension of the spoken word, but only for the impaired semantic category. This pattern of performance is interpreted as evidence for a degree of autonomy for the semantic processing of written words.