Recent increases in breast-feeding in the United States have renewed interest in its associated health effects. In addition to known protective effects related to diarrheal disease in infancy and allergies, breast-feeding may be related to other health and developmental concerns with health cost implications. Data from the Child Health Supplement to the 1981 National Health Interview Survey were analyzed to assess the association between breast-feeding and malocclusion. Increased durations of breast-feeding were associated with a decline in the proportion of children with malocclusion, an association that remains when controlled for known associated variables. Our study adds sufficient strength to the findings in this area that we can recommend that health practitioners inform expectant mothers about this additional benefit of breast-feeding.