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, when using a flapless computer guided implant surgery and tissue-supported computer aided surgical stents. Fifteen completely edentulous patients were recruited from Outpatient Clinic, Prosthodontic Department, Faculty Of Oral and Dental Medicine, Cairo University. After complete denture construction a radiographic template was fabricated from denture duplication. The patients were imaged using CBCT and the DICOM data were imported to computer software for virtual implant planning. The virtual surgical guide was sent for prototyping to construct a computer-guided stent. Surgical execution of implants was done using the fabricated stents. Four implants were placed in each arch. 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 deviation, lateral deviation, vertical deviation and finally angular deviation.The patient received at the end of the study a screw-retained prosthesis on four implants in each arch. The results of the study revealed that there was no statistical significant difference between the virtual planning and actual execution of the maxillary and the mandibular implants. However, the results showed higher deviation in the mandible in the mesiodistal plane in the coronal global linear from the virtual planning. While there was a higher deviation in the maxilla in the buccolingual plane in the coronal lateral deviation from the virtual planning.