A serologic screening for toxoplasma antibodies by dye test (DT) and IgG indirect fluorescent antibody test (IgG-IFAT) has been carried out among 10729 pregnant women in the Oslo area and 1 007 pregnant women from the county of Møre and Romsdal situated on the west coast of Norway. The frequency of toxoplasma antibodies was found to be higher in women living in rural areas and a higher prevalence was observed among women living in the western districts of Oslo than among women from the eastern districts of the city. The mean frequency of DT antibodies was found to be 12.5% in the Oslo area and 13.3% in Møre and Romsdal, whereas the yearly incidence of acquired infections in the two areas was found to be 5 and 2.3%, respectively. The predicted incidence of congenital toxoplasmosis in the Oslo area, and presumably also in the whole country, would represent 2% of all pregnancies. No serologic differences were found when women with prior histories of either sporadic or habitual abortions were compared to a total group of multigravidae among the Oslo women.