A letter to the editor entitled “Folic Acid Requirements for Women of Childbearing Age” (December 1999, page 2510) contained an error in the dosage unit for folic acid, which occurred in the publishing process. The author, a representative of the March of Dimes, had originally supplied the correct folic acid dosage and emphasizes that supplementation with 400 μg of folic acid per day in women of childbearing age is an important measure in reducing birth defects.