In Italy, drug abusers are the major risk category for HIV infection, representing 67% of all the reported cases of AIDS. This can in part explain the higher incidence of the infection observed in Italian females (17.7%) in comparison with the data reported in Europe (11.5%) or in the U.S. (8.5%). Therefore, anti-HIV screening in newborns reflects the serologic pattern of the respective mothers and can provide a useful tool in evaluating the incidence of the infection in a relatively unselected population. Furthermore, the data collected can provide a good predictive parameter for the rate at which pediatric AIDS will develop. Blood samples were collected on filter paper for routine screenings from 39,102 consecutive newborns in 92 hospital nurseries, from eight different Italian regions, during the period June 1988-April 1989. Blood-saturated disks were screened for anti-HIV antibodies (HIV Ab) using an ELISA; positive results were confirmed using a Western blot. Among the 39,102 blood samples tested, 51 (0.00130, 95% confidence intervals, Poisson distribution of 0.00097-0.00171) were found to be positive for HIV Ab. The distribution pattern of the positive samples among the different regions correlates to the cumulative AIDS incidence rate, with a higher prevalence in urban and industrialized areas.