Introduction: The varicella-zoster virus (VZV) poses a risk of maternal-fetal complications in seronegative women. A cross-sectional study was conducted to determine the seroprevalence of VZV among pregnant women and to assess the positive predictive value (PPV) and negative predictive value (NPV) of a history of chickenpox. Methods: From November 22 to December 10, 2005, 486 women were recruited from 18 medical testing laboratories located in various districts of Lyon and its surrounding areas. Sociodemographic characteristics and history of chickenpox and shingles were collected via a questionnaire. A blood sample was used to test for IgG against chickenpox (ELISA). Results: The seroprevalence of immunity to VZV was 98.8%. The number of seronegative women was six, four of whom were primiparous. The positive predictive value (PPV) and negative predictive value (NPV) for a history of chickenpox were 99.5% (369/371) and 10.3% (3/29), respectively. Discussion: The seroprevalence of VZV in this population is high. Protection against VZV infection during pregnancy could not be established for approximately 1% of the participants. The low NPV of the questionnaire indicates that a negative history of chickenpox should be supplemented by serological testing, which can be requested as part of any routine infectious disease screening during pregnancy. (R.A.)