Toxoplasma-specific antibodies transferred across the placenta were determined in 1953 blood samples of newborn infants from the Lower Saxony newborn-screening-laboratory using the indirect immunofluorescence test. There were no antibodies demonstrable in 54.4% of the samples. Related to the age of the mothers there was increase of positive findings of about 1% per year. Among 10 000 pregnancies about 70 to 80 mothers can be expected to undergo a primary infection with Toxoplasma gondii. With a fetal infection rate of about 50% derived from the literature 30 to 40 cases of congenital toxoplasmosis of variable severity, three among them serious, may be expected.