Aim: The aim of this study was to evaluate the effect of asthma on dentoalveolar morphology. Methods: Fifty asthmatic Egyptian children were compared to another fifty non-asthmatic by dental cast analysis for upper and lower intercanine width (UICW-LICW), upper and lower intermolar width (UIMW-LIMW), upper and lower arch length (UAL-LAL) and palatal depth (PD). Results: Children with asthma showed high mean values in more than one of parameters, when compared with mean value of non-asthmatic children in both gender. While upper inter molar width of asthmatic children had less mean values when compared with mean value of non-asthmatic children as general, except when compered regarding to gender. When calculated by the t-student test, a significant difference was detected in upper inter molar width in male, lower inter molar width, and in male. Conclusion: Asthma has an effect on upper and lower dental arch dimensions in both gender.