Objectives: The study aims at comparing the development areas of newborns/children who have been diagnosed with congenital hearing loss through newborn hearing screening at earlier stages with newborns/children in the same age group who do not have hearing loss.Material and Methods: Fifty newborns/children diagnosed with congenital hearing loss through newborn hearing screening and 50 newborns/children in the same age group who have normal hearing were included in the study. The development of both groups was assessed with the Ankara Developmental Screening Inventory (AGTE) and Vineland Behavior Adaptation Scale. Results: The AGTELanguage Cognitive (Dil-Bilişsel-DB) and AGTE-General Development (Genel gelişim-GG) and V-Communication, V-Socialization and V-Compatibility Level test scores of infants/children with hearing loss were significantly low compared to infants/children with normal hearing (p<0.05). Regarding the aims of the newborn hearing screening, comparison between infants/children who have been diagnosed early (0-6 months of age) and late (7 months of age and above) revealed significantly higher scores in AGTE-DB, AGTE-GG, V-Communication and V-Compatibility Level tests in the early diagnosed group (p<0.05). Infants/children with profound hearing loss had lower scores in AGTE-DB, V-Receptive Language, V-Expressive Language and V-Socialization tests (p<0.05) than the normal hearing group. The AGTE and VUDO test scores (p>0.05) did not show a significant difference between infants who used hearing aids at early (3-6 months of age) and late (7 months of age and above) stages. Conclusion: Newborn hearing screening allows early diagnosis, early use of hearing aids and auditory habilitation at an earlier age, as well as intervention within the critical period for infants with hearing loss, in terms of the development of cortical perception. Although infants/children with hearing loss have delays in language development and developmental areas based on language in comparison to their peers, infants/children who have been diagnosed early show better performance in language development and general development areas compared to infants/children who have been diagnosed late. Newborn hearing screening is of major importance in decreasing the negative effects of hearing loss and in the early intervention to hearing loss. © 2012 by Türkiye Klinikleri.