A case of crossed dextral aphasia characterized by agrammatism was reported. The patient,55-year-old purely right-handed man, a teacher of Japanese, developed left hemiparesis, slight left unilateral spatial neglect and aphasia because of cerebral infarction. CT scan displayed a large hypodense area in subcortical region of the right hemisphere. His speech showed slight dysarthria, literal paraphasias and agrammatism. The characteristics of the agrammatic speech were as follows : dropping out of grammatical morphemes (including joshi, auxiliary verbs and conjugation of verbs), good word-findings, lots of pauses in spite of long and well-constructed sentences. The writing had some literal paragraphias and agrammatism such as in speech. The way of writing was disorderly. Grammatical morphemes and verbs in part were regarded as representing speaker's thought and attitude essentially, and in case a speaker's tension to maintain his intention of speech was reduced, they would be apt to be dropped. We pointed out that the mechanism of writing disturbance of this case was different from non-crossed left hemisphere damaged aphasic's, and that such aphasic symptom as this case might represent a type peculiar to crossed dextral aphasia.