Background: Implant therapy is now considered an acceptable successful way to replace hopeless teeth. the purpose of this study was to Evaluate the use of gingival mesenchymal stem cell (GMSC) on chitosan scaffold in the treatment of peri-implant defects. Method: A total of ten mongral dogs age ranging between 1 to 2 years old weight from 20 to 25kg were used in the current study. Dogs were scheduled for first premolars extraction one on each side and immediate replacement by immediate implant at mesial socket with creation of peri-implant defect at distal socket. Sites were randomly assigned in a split mouth design into two groups: control group in which the defects were filled with chitosan only, intervention group in which the defects were filled by Gingival Mesenchymal Stem Cells (GMSCs) carried on chitosan scaffold. Five dogs will be sacrificed 1month and the others will be sacrificed at 3 months post operation. Bone density was measured around each implant at defect sides at baseline (implant insertion), 1 month and 3 months. Results IBM SPSS 28 for windows software was used for the analysis, there was a significant difference in bone density change, as bone density change was higher in intervention group, p-value > 0.05 at one month but there was no statistically significant difference observed between the two groups at three Oral medicine, Diagnosis and periodontology department Faculty of Dentistry Minia University Egypt  Conclusion:using gingival mesenchymal stem cells in treatment of peri-implant defects gives better results in shorter duration, but same results can be reached with chitosan alone in longer duration and less costs. More studies with larger sample size are recommended.