Toxoplasmosis is a widely distributed disease with prevalence rates ranging between 40 and 80% in different parts of the world. The diagnosis of congenital toxoplasmosis constitutes a health problem since intra-uterine infection can lead to undesirable effects on the fetus. Immunoenzymatic methods are the techniques of choice for the serologic diagnosis of toxoplasmosis. The present paper describes an indirect sandwich ELISA with the murine anti-P30, the main surface antigen of Toxoplasma gondii, monoclonal antibody as the first antibody fixed to the polystyrene 96 wells plate for the capture of P30 molecule from T. gondii extracts and to detect the presence of human anti-P30 IgG. Serum samples from 42 pregnant women were studied and compared to results obtained with a commercial kit (Plastelia Toxo IgG, Institute Pasteur, Lille, France) for the same purpose, in which 83.4% of the serum samples were positives. Our results demonstrated a significant correlation (p < 0.001; r = 0.84) with those obtained with the commercial kit. We conclude that the IgG anti-P30 method should be very useful for screening of seroconversion in pregnant women not sensitized by T. gondii and to evaluate epidemiologically the prevalence rate infection by this parasite which can cause and transmit this disease subclinically.