OBJECTIVE: To describe the prevalence of neural tube defects (NTDs) in Victoria, and to evaluate women's knowledge and awareness of the importance of folate after the introduction of voluntary food fortification. DESIGN AND SETTING: Descriptive study, set in Victoria, Australia, based on routinely collected data from the Victorian Birth Defects Register (VBDR) for 1998-2006, and responses by women aged 18-50 years to five questions relating to folate on the 2005 and 2006 Victorian Population Health Surveys (2314 and 2488 women, respectively). MAIN OUTCOME MEASURES: Prevalence of NTDs, and extent of women's knowledge of the importance of folate in NTD prevention, comparing the period before and since voluntary food fortification and a folate awareness campaign. RESULTS: The total prevalence of pregnancies affected by NTDs declined from approximately 17 to 14 per 10,000 births from 1997 to 1999 (coinciding with the period when voluntary food fortification was introduced, and a 1-year folate awareness campaign was held). It has since remained static. Over the 9-year study period, the termination of pregnancy rate was 79%, resulting in three NTD-affected babies per 10,000 livebirths. Compared with women aged 30-34 years (the reference group), those aged 20-24 years had the greatest likelihood of having a baby with an NTD (adjusted odds ratio, 1.70; 95% CI, 1.33-2.18; P < 0.001). Women aged 18-24 years had the lowest rate of folate supplement use (15.9% in 2006), while women aged 30-34 years had the highest rate (30.3% in 2006). CONCLUSIONS: There has been no further reduction in prevalence of NTDs in Victoria since 1999, and this prevalence remains well above that achievable through adequate folate intake. Accurate knowledge of folate consumption, population-based NTD prevalence data and folate awareness data are essential in monitoring the effectiveness of the mandatory fortification program to be implemented in Australia in the next 2 years.