This study examined the relationship of a compromised airway in asthmatic children, i.e. mouthbreathing, and the effect that the airway compromise has on occlusal and facial characteristic. The study consisted of sixty-four children of both sexes, ranging in age from three to sixteen years. Thirty-two subjects were from the pulmonary and allergy clinic of the Floating Hospital, New England Medical Center, who were present for follow-up and/or treatment of asthma. Thirty-two randomly selected children were selected from the pediatric clinic in Tufts University School of Dental Medicine to serve as controls. The two groups were equally balanced according to age, sex and race. A statistically significant relationship was found between the frequency of crossbites and the frequency of mouth breathing. Additionally, a statistically significant relationship was found between the frequency of crossbites and the facial type in the experimental group. The frequency of crossbites appears to be related to abnormal facial types.