This quasi experimental study was conducted to compare the amount of linear and angular deviation between the virtual position of implants in the preoperative plan and their actual execution into the patient’s mouth postoperatively, when using a flapless computer guided implant surgery and tissue-supported versus tooth support computer aided surgical stents.Twelve (group I six completely edentulous patients, group II six partial edentulous patients) were recruited from Outpatient Clinic, Prosthodontic Department, Faculty of Oral and Dental Medicine, Cairo University.Radiographic templates were constructed for both group I and II. Then patients were then sent to a CBCT scan and the DICOM data were imported to computer software for virtual implant planning. Then a three dimensional virtual stent was designed then processed by a rapid prototyping unit and built from a photo curable resin material.Drilling for the implant was done with the surgical stent secured in its place. After preparation of the osteotomy sites, the implants were placed with the implant mount using a ratchet.The patients then received a postoperative CBCT scan and the data were sent to the computer software for superimposition. Four parameters were used to measure the amount of deviation named global, lateral, vertical and finally angular deviation.5-2The patient received at the end of the study (group I crown and bridge restoration while in group II screw-retained prosthesis).