Introduction - Toxoplasmosis is transmitted through the ingestion of contaminated food or contact with an infected cat. During pregnancy, Toxoplasma can cause eye damage in the fetus or, more rarely, severe, potentially fatal neurological lesions. The objectives of this study were to estimate the prevalence and incidence of toxoplasmosis in 2003 among women of childbearing age and to investigate the sociodemographic factors associated with toxoplasmosis. Subjects and methods - The study population consists of all women from the 2003 National Perinatal Survey (ENP 2003). A multivariate analysis was performed on several socioeconomic variables. A mathematical model using seroprevalence data from the two national perinatal surveys (ENP 1995 and 2003) was used to estimate incidence rates by age and region. Results - Among the 15,108 pregnant women included in the ENP 2003, the prevalence of toxoplasmosis was 43.8%. This prevalence increased with age, was high in the Southwest (50%), in the Paris region (52.7%), and in the French overseas departments (54.8%), and low in the Northeast (29.5%). It was lower in colder geographic areas and increased with the consumption of sheep meat. Between 1995 and 2003, prevalence and incidence rates fell by nearly 20%. In 2003, the incidence rate was estimated at between 6 and 7 per 1,000 pregnant women, depending on their age, but this rate varies greatly between regions. Discussion - The prevalence of toxoplasmosis has declined sharply over a seven-year period. If this decline continues, an evaluation of the effectiveness of the current prevention program should be considered. (R.A.)