Objectives: now a days recent intraoral scanners (IOS) are ready for digital scans of long-span edentulous patients and completely edentulous patients ; however, there is lacking of evidence. In recent years there is vigorously promoted of digitization in the dental field there is a significant transformation in the future of dentistry by using the intra oral scanner to have digital impression. The aim of this article to evaluated the deviation between of intraoral scanning (IOS) impression and conventional impression in completely edentulous patient and to analyze the accuracy of IOS in completely edentulous maxillary arch. Materials and methods: Two types of impression technique were made for eight completely edentulous patients. Intra oral scanning and conventional impression technique of the maxilla was done for each patient, the two-impression techniques were compared for accuracy using GOM inspect software. Result: Total deviation between two groups were compared to hypothesized zero representing conventional impression I group and then calculated using special inspection software. The total deviation was statistically significantly different among the studied groups. Conclusion: The accuracy of IOS not reliable for completely edentulous arches