We present an unusual case of crossed aphasia in a doctor who is totally right handed, following an infarction which almost completely destroyed his right hemisphere. The observations--linguistic and extra linguistic--during a study over two years are presented. The aphasia evolved in three stages, taking semiological and evolutive aspects not commonly met with. In speech and writing there were: 1. an oral agrammatism and a written dyssyntaxia in the initial stage; 2. the evolution of a non-fluent speech typically agrammatic leading to a jargonaphasia; 3. a dissociation between oral and written language, characterised by phonemic paraphasias in speech and dyssyntaxia in writing. Comprehension was good except for a verbal class called "empty signs" of language, in which the lexic which refers to the notion of space and time has a primary role. On an extra linguistic level some of the usual signs of right hemisphere lesions were present indicating disturbances of a spatial type. The patient could no longer grasp the concept of numerical value and showed severe difficulties in relation to time. On a linguistic level, the discussion is first considered from a typological point of view; this allows to compare our patient's disorders with a Broca's then with a conduction aphasia, Secondly, the discussion is considered from a semiological point of view, taking into consideration the 10 selected cases in the literature and adding our own; a semiological formula of crossed aphasia is given: agrammatism and/or dyssyntaxia + phonemic paraphasia and/or dysorthographia. A suggestion concerning the role of each hemisphere in the language of our patient is proposed: the possible role played by a congenital deafness in the right ear (discovered in the patient at the age of 8) to explain this abnormal hemispherical functional specialisation is discussed. Original comprehension difficulties concerning the time-space lexic are replaced by a perspective of a cognitive type. We conclude that in our patient, there was a "breakdown" of time and space which comes close to the "indifferenciation" of spatial order and time which Piaget has described in children.