DESCRIPTION: In 1996, the U.S. Preventive Services Task Force (USPSTF) recommended that all women planning or capable of pregnancy take a multivitamin supplement containing folic acid for the prevention of neural tube defects. This recommendation is an update of the 1996 USPSTF recommendation. METHODS: The USPSTF reviewed the evidence on folic acid supplementation in women of childbearing age published since the 1996 USPSTF recommendation. The USPSTF did not review the evidence on folic acid food fortification, counseling to increase dietary intake, or screening for neural tube defects. RECOMMENDATION: The USPSTF recommends that all women planning or capable of pregnancy take a daily supplement containing 0.4 to 0.8 mg (400 to 800 microg) of folic acid. (Grade A recommendation).