Introduction: With age, the sinus walls become thinner gradually and lead to sinus pneumatisation in the posterior maxilla which complicates implant placement. Sinus floor augmentation is one of the most important approaches to increase the remaining bone height in the maxilla; to provide sufficient bone for implant stability.Aim of the study: The objective is to test the hypothesis that there is no difference in implant treatment stability outcome using PRF over (in comparison to) autogenous bone graft for internal sinus floor augmentation. Materials and methods: This study was conducted on ten patients (4 males and 6 females) with age ranging from 35 years old to 45 years old. The selected patients were requiring single or multiple implant placements in the maxillary posterior region, admitted to the Outpatient Clinic of Oral Medicine, Diagnosis and Periodontology department, Faculty of Oral and Dental Medicine, Cairo University. Clinical parameters were recorded for the surrounding dentition before any intervention for periodontal evaluation. These parameters include, Plaque index, Gingival index Probing depth and Clinical attachment level. Surgical technique was done as follows, under local anaesthesia a flap was raised to expose the surgical site. With the aid of CBCT, location of the sinus was known. An osteotomy site was performed using the pilot drill until the wall of is sinus is reached then osteotomes were used in an ascending manner to raise the sinus membrane. The last osteotome to raise the sinus membrane 4mm beyond the floor of the sinus. Randomly, PRF and autogenous bone grafts were used before implant placement.Results: Radiographic assessment showed both PRF and autogenous groups resulted in gain of subsinus height when baseline and postoperative readings were compared after 6 months. PRF showed promising augmentation results in implant stability using periotest measurements compared to autogenous bone augmentation although statistically non-significant.There was no statistically significant difference between mean % changes in Periotest scores of the two groups were the level of significance was P ≤ 0.05.Discussion and conclusion: Results of the present study was in accordance to the results of the previous studies by were they also showed promising results for implant stability when using PRF as a sole grafting material for sinus floor augmentation