The article describes the case of a child with an profound prelingual hearing loss considering etiology, pathomechanism of speech disorders and results of the diagnosis. Linguistic and communication skills were taken into consideration in the child’s detailed analysis and assessment. Besides, observations and family interviews were implemented to the following research methods in order to evaluate levels of psychomotor development, hearing perception, motor skills of the speech apparatus, pronunciation, the child’s mental lexicon, narrative skills, reading and writing skills. Thanks to the case study we could create dynamical picture of the hearing-impaired child speech development, and acquire linguistics and communicative abilities, define the results of earlier therapeutic process and determine its next stages.