The finding that early detection of permanent congenital childhood hearing loss produces worthwhile benefit in terms of improved speech and language provides the rationale for the universal screening of newborns. The aim of the present study is to collect the current evidence with regard to the efficacy, the results and outcomes of universal hearing screening programs. An extensive search of the literature was performed in Medline and other available database sources. Study selection was based on the evaluation of the protocols used and the assessment of their efficacy in the early diagnosis of congenital hearing impairment. The initial referral rate and the rate of false positives were also evaluated. A total of 676,043 screened children have been identified in 20 studies. The average initial referral rate in these studies was 3.89%. The initial referral rate varied from 0.6 to 16.7%. The lost-to-follow-up rates varied from 3.7 to 65%. Although universal hearing screening is now widely adopted, there are still some serious drawbacks and limitations. False positives rates remain considerably high when newborns are screened with TEOAE's. The combination of TEOAE's and a-ABR provides a significantly reduced referral rate. Close cooperation between audiological centres and maternity units and a dedicated secretariat team are of paramount importance with regard to the reliability and efficacy of universal hearing screening.