1. Some characteristics observed in the development of written and spoken language of an 11-year-old boy (examined initially at age 6) complaining of dyslexia and dysgraph ia were studied. 2. In the written language, he had difficulty associating configurations of letters directly with their sound referents in hiragana, kanji and numbers. He learned to establish associations between them by intervention of semantic meaning. 3. In the spoken language, a limited vocabulary and paraphasia and difficulty in picture naming tasks were observed. 4. Specific features in acquiring letters and error analysis of his acquired reading and writing suggested that he had a functional impairment of the association between visual information conveyed through the visual modality and auditory-verbal information transmitted through the auditory-verbal modality. 5. Careful observations of his naming difficulties indicated that he made fewer errors in naming tasks when only a single (i. e., auditory-verbal) modality was involved than when two (i. e., visual and auditory-verbal) modalities participated in the tasks. 6. Some of the characteristics of his written and spoken language to a certain extent resembled the symptoms of alexia with agraphia in adults and of language disorder syndrome, a type of developmental dyslexia.