Background: There has been suspicion that service in the Persian Gulf War affected the health of veterans adversely, and there have been claims of an increased rate of birth defects among the children of those veterans. Methods: We evaluated the routinely collected data on all live births at 135 military hospitals in 1991, 1992, and 1993. The data base included up to eight diagnoses from the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) for each birth hospitalization, plus information on the demographic characteristics and service history of the parents. The records of over 75,000 newborns were evaluated for any birth defect (ICD-9-CM codes 740 to 759, plus neoplasms and hereditary diseases) and for birth defects defined as severe on the basis of the specific diagnoses and the criteria of the Centers for Disease Control and Prevention. Results: During the study period, 33,998 infants were born to Gulf War veterans and 41,463 to non-deployed veterans at military hospitals. The overall risk of any birth defect was 7.45 percent, and the risk of severe birth defects was 1.85 percent. These rates are similar to those reported in civilian populations. In the multivariate analysis, there was no significant association for either men or women between service in the Gulf War and the risk of any birth defect or of severe birth defects in their children. Conclusions: This analysis found no evidence of an increase in the risk of birth defects among the children of Gulf War veterans.