The correct usage of folic acid (FA) supplements to prevent neural tube defects (NTDs) increased from 28% in 1996 to 50% in 2005 and remained stable until 2009. Recent data from national birth defect registries show a decrease of NTD prevalence from 13.2 (per 10,000) in 1997 to 8.3 in 2005 and stabilization up to 2009. It is estimated that between 2005 and 2009 FA supplementation prevented 583 NTD cases. The medical costs thus averted are € 75 M. If the correct usage of FA were to be increased to 70%, another 34 cases per year could be prevented. Part of the gain from continued prevention and other averted costs should be invested beforehand in the promotion of FA supplement usage.