The detection of group B streptococci by the ICON Strep-B test an enzyme immunoassay, and culture in new Granada Medium was compared in tubes and plates in a total of 200 vaginal specimens from pregnant women. The group B streptococci were cultured in new Granada medium from 33 of these specimens (incidence of 16.5%). Compared with culture in new Granada medium, the sensitivity and specificity of the ICON-Strep B test were 66.6 and 100%, respectively. Because of their poor sensitivity, we do not recommend the use of these rapid test as the only basis for GBS detection.