Objective: In November 1993, Dutch health authorities advised that women planning a pregnancy should take folic acid in the periconceptional period to reduce the risk of fetal neural tube defects. In the autumn of 1995 a national campaign was organized to inform women and health care professionals in a systematic way. Methods: We assessed the awareness and behaviour of women at their first or second antenatal visit in two surveys in the spring of 1994 and the autumn of 1995, in order to evaluate the impact of non-systematic information during that period, and to collect baseline data to evaluate the effect of the national folic acid campaign. The two surveys were carried out in the north and the west of The Netherlands. Results: The proportion of women who had heard of folic acid increased from 28% to 78%. The proportion that used folic acid during any period in pregnancy increased from 7.8% to 26%. The proportion that took folic acid tablets during the whole of the recommended period increased from 0.8 to 4.4%. In the group of women wits did not take folic acid, the proportion who did 'not like to use anything during pregnancy' decreased, as did the proportion who did 'not think it is useful'. Conclusion: In The Netherlands, non-systematic information about periconceptional folic acid use has already led to significant changes in awareness and behaviour before the start of the national folic acid campaign.