This research was designed to provide an insight into the state of occlusal patterns, tooth size and arch dimension of the primary dentition in a group of preschool Egyptian and Yemeni children. A total of 1113 Egyptian and Yemeni children aged from 3-5 years were examined. A sample of 597 children (320 girls and 277 boys) was selected from the examined children to meet the following criteria; to have a full complement of primary dentition, no missing teeth, no interproximal carious lesions and to be free from any dental malformations. Children with systemic health disease or children with...