Background:
Language communication is necessary for social and emotional development of each person. This applies particularly to deaf children. In the case of profound hearing loss it is very important to early apply a cochlear implant system, increasing the range of information reaching the child in the auditory way. This has a huge effect on speech understanding and evolution of mental processes. It allows the child, with an additional and regular rehabilitation, to achieve a much higher level of language development and acquisition of knowledge about the world than children without this appliance. The sooner a child has the opportunity of hearing and rehabilitation, the easier it will adopt in the environment of the hearing

Aim:
The object of the study was the diagnosis and therapy of two children with a cochlear implant system at preschool age. The aim was to show the overall functioning at different levels: cognitive, motor, emotional and, above all, the communication level of deaf children with cochlear implant.

Method:
The research method used was the individual case method, aiming at the reliable diagnosis as well as the preparation and conducting of appropriate speech therapy. Direct observation of the tested children helped to evaluate their development in various spheres of life. The tested children had a very different family situation.

Results:
The boy was neglected by his parents, however the girl owed the good functioning in language communication to intensive rehabilitation and systematic stimulation of auditory and linguistic skills in the family environment. Consequently, the children’s communication difficulties varied. At the age of 5, the boy spoke just a few words heard from the environment but the girl reached the level of development of a 6-year old child.

Conclusions:
The results showed that difficulties in the use of speech occur in the absence of rehabilitation and systematic help in the family environment in which the child with an implant develops. Diagnosis and speech therapy should take into account the level of language development and learning opportunities of the children with implants. Close cooperation with the family is crucial. Especially children with difficult family situations should be provided with psy