The discovery that folic acid can reduce neural tube defect rates offers a great opportunity for primary prevention. Unfortunately, women must receive the folic acid before or immediately after conception, before many know that they are pregnant. Thus, we are faced with a difficult choice: (1) ask all women at risk of getting pregnant to take supplements, or (2) fortify the food supply to ensure that all women at risk receive additional folic acid. Neither approach is ideal. Many women will not take vitamin supplements. Fortification at sufficiently high levels to provide all women with 400 micrograms of folic acid will expose other segments of the population to unacceptably high levels. Because many women of child-bearing age are unaware of the benefits of folic acid, a vigorous education campaign should begin immediately to encourage women at risk to take supplements. Adding 70 micrograms of folic acid per 100 g of grain could be justified easily because this amount is removed from grain in processing. If it is technically feasible, adding up to 140 micrograms is likely to be safe, and could prevent more NTDs. A major educational campaign and modest fortification of grain with folic acid may be the best practical solution.