The National Birth Defects Prevention Study (NBDPS) is an ongoing, multicenter, case-control study of over 30 major birth defects, and is one of the largest studies of the causes of birth defects to date. Data from it were examined to determine if maternal or paternal military service since 1990 as reported during the interview was associated with birth defects among offspring. Logistic regression was used to produce odds ratios (ORs) adjusted for major confounders. Overall, the results indicated no statistically significant association between parental military service since 1990 and increased risk of birth defects.