Background: For severe to profound deaf persons, cochlear implantation has been used as a successful procedure to regain partial hearing. The variability seen in language and speech development after cochlear implantation is due to contribution of multiple factors not only demographic and hearing history but also neurological and cognitive factors. Objectives: The aim of this study was to explore the effect of different variables as age of implantation, duration of CI use and preoperative IQ score on auditory and language development of prelingual cochlear implanted children. Methods: This study included 62 participants operated in zagazig university hospital and follow the candidacy criteria for cochlear implantation of Zagazig University CI program. All patients were subjected topostoperative audiological and phonological assessment including Warble tone response thresholds in sound field, aided speech discrimination, language test and speech analysis. Results: The results of the study proved that the better outcomes of CI children are correlated with younger age at implantation, longer duration of CI use, preoperative improvement quotient. Conclusion: Better speech and language development were significant correlated with earlier age at implantation, better IQ score, longer duration of CI use.