Routine anti-HIV screening of 36,053 sera from pregnant women in South-Eastern Norway yielded four (0.011%) true positive individuals. Three of these were known to be HIV-infected before pregnancy. In addition 23 women (0.064%) gave false positive results. Fifty (0.14%) women actively refused anti-HIV test. Anonymous testing of the sera from these women probably yielded one single true anti-HIV positive (2%). The prevalence of HIV-infection among pregnant Norwegian women is very low. Nevertheless, this screening programme could be instrumental in the future for the indirect monitoring of the incidence and prevalence of HIV-infection among the sexually active section of the population. False positive results were rare and caused no real diagnostic problem.