OBJECTIVES: To determine whether implementation of universal newborn hearing screening (UNHS) in the state of Illinois has affected the ages at diagnosis of hearing loss and implantation in children receiving cochlear implants and to determine how often children undergoing implantation had UNHS results with no indication of hearing loss (pass). DESIGN: Retrospective case review of 417 randomly selected pediatric implant recipients born before and after UNHS was mandated by law in Illinois. Data analyzed included hearing screening status, ages at initial diagnosis of sensorineural hearing loss (SNHL) and severe to profound SNHL, and age at implantation. SETTING: Tertiary care medical center. PATIENTS: Children receiving implants from 1991 through 2008. MAIN OUTCOME MEASURES: Ages at diagnosis of SNHL and implantation. RESULTS: Children born after legally mandated UNHS had significantly younger ages at diagnosis and implantation. However, a younger age at diagnosis of SNHL was not achieved in children who had passed UNHS or who were not screened. Approximately 30% of pediatric implant recipients passed UNHS, regardless of the cause of hearing loss or the presence or absence of known risk factors. CONCLUSIONS: Almost one-third of our pediatric implant recipients pass UNHS and are older at the time of initial diagnosis and implantation than their peers who fail UNHS. Delayed onset of SNHL limits our ability to achieve early diagnosis and implantation of a significant number of deaf children. This problem will not be solved by the current design of universal hearing screening programs.