A comparative evaluation of the Abbott AxSYM and DPC Immulite random-access analyzers was performed using 497 prospectively collected serum samples. These samples were sent to the laboratory for routine antenatal screening for hepatitis B surface antigen and immunoglobulin G (IgG) and IgM antibodies to Toxoplasma gondii and rubella virus. The overall agreement between the two assay systems ranged from 97.4 to 100%. After discrepancy analysis, the outcome in terms of sensitivity and specificity varied from 98.2 to 100% for all but one of the assays tested. The AxSYM rubella virus IgG assay tended to report protective or indeterminate antibody levels in 1% of the samples. This shortcoming might be overcome by raising the cutoff of the microparticle enzyme immunoassay system. Toxoplasma gondii and rubella virus (RV) infection both cause a generally benign disease in immunocompetent individuals (3, 9) but may lead to congenital infection with serious sequelae for the newborn after primary infection in pregnant women.Primary maternal RV infection during the first trimester of pregnancy carries a high risk for the development of the congenital rubella syndrome with characteristic malformations of the heart, eye, and ear. Although rubella vaccination has reduced the incidence of RV infection substantially, maternal infection in industrialized countries is still estimated to occur in 1 out of 6,000 to 10,000 pregnancies (1).A high proportion of pregnant women are seronegative for T. gondii and therefore at risk for primary T. gondii infection and, subsequently, for the development of congenital toxoplasmosis in their offspring (6). Symptoms, like chorioretinitis and delay in development, can be prevented if timely treatment with spiramycin is initiated (4).It is therefore of utmost importance to identify susceptible women in order to offer early treatment. Screening programs for pregnant woman are now available in various Western countries (7,14). Most recently, hepatitis B has been added to these screening programs, because hepatitis B vaccination of the newborn can actually prevent transmission from an HBsAg-positive mother to her child (12).Antenatal screening programs produce a substantial workload for the microbiological laboratory. Testing of large numbers of serum samples has shifted in recent years from batch-processing enzyme immunoassays to sophisticated random-access systems capable of processing a variety of tests simultaneously.In this study, we compared the results obtained from the Abbott AxSYM and DPC Immulite systems during routine antenatal screening for HBsAg and for immunoglobulin G (IgG) and IgM antibodies to T. gondii and RV. MATERIALS AND METHODSThe evaluation, which ran from August to November 1999, included blood specimens referred to the medical microbiology laboratory for antenatal screening. Blood samples were clotted and centrifuged prior to testing. All sera were then tested for the presence of HBsAg and for IgG and IgM antibodies to RV and T. gondii with the Abbott AxSYM and DPC Immulite s...