Many factors affecting the lung functions, directly or indirectly, including anthropometric values, nutritional state, and body mass index. The aim of this study (First study in the middle Egypt, Assiut governorate) was depending on estimation of predication equation reference; establish normal spirometric values with age from 20-45 years in both genders. Furthermore, we compared our result with previous studies in our Arabic area as well as united state (US) population. The prediction equation in Assiut area governorate is including the height besides, age and weight. From results, it was found that the spirometric values and the prediction equation in males are better than female. It is in agreement with Jordanian male but less in female. While our results in both male and female is less than US population. It is concluded that prediction equation in our area in Egypt is including weight and the spirometric values in females is less than males. These results are in agreement with other Arabic studies (Jordanian rather than Omani). The spirometric values in our area similar to Arabic area and are less than US population which maybe due to differences in anthropometric features, genetics as well as dietary habits.