Background: Toxoplasma gondii infection during pregnancy causes congenital malformations. Pregnant women should be screened for this infection since it is preventable and treatable. Aim: To study the seroprevalence of Toxoplasma gondii infection among pregnant women living in Izmir, Turkey. Material and Methods: A blood sample was obtained from 4651 women aged between 15 and 45 years, during their first trimester of pregnancy. IgM and IgG antibodies against Toxoplasma gondii were measured using an ELISA assay. Among women with both IgG and IgM antibodies positive, an IgG avidity test was performed, using a VIDAS kit. Results: IgG antibodies were positive in 1871 (39.9%) participants. Of these, 48 (2.5%) also had positive IgM antibodies. In 41 of these 48 women, the IgG avidity test was performed and only one woman had a low avidity. This woman was treated with Spiramycin. Her offspring had an intrauterine growth retardation and oligohydramnios. A chorioretinitis was diagnosed in the offspring of other woman with both antibodies positive. Conclusions: In this series, the prevalence of congenital toxoplasmosis was low. However, women with positive antibodies against Toxoplasma Gondii should be further studied and followed during their pregnancy.