Objective: To evaluate the prevalence of the awareness of and the behaviour towards folic acid in 2003 and the trend of folic acid use among pregnant Dutch women between 1995 and 2003 with regard to socio-economic status (SES). Method: We conducted 2-yearly cross-sectional studies among pregnant women who filled in a questionnaire during the first or second antenatal visit. The highest achieved level of education was taken as a proxy for SES. Results: In 2003 the general level of folic acid awareness was high but with significant differences relating to SES; a quarter of the lower educated women did not know about folic acid before pregnancy. Of the subjects with a lower SES 20% knew the correct period of use compared with nearly 50% in the higher SES group. The reported correct use of folic acid among the lower educated women has decreased over the past 3 years (22% in 2003), while it has increased for the higher SES groups (59% in 2003), implying larger differences in health. Conclusion: In 2003, 8 years after a mass media campaign, awareness and use of folic acid were increased considerably in comparison with the start of the campaign. However, differences in knowledge and use of folic acid with respect to the level of education had never been so impressive in the Netherlands as in 2003. A once-only campaign has a short-term effect especially for lower educated women. Implementing strategies to promote folic acid use in daily structural health care systems are needed. Copyright (c) 2007 S. Karger AG, Basel.