Presence of pneumatized sinus in the posterior maxilla is a frequent anatomical obstacle impairing implant placement. It is usually occurs as a result of gradual thinning of sinus walls with aging and reduction of maxillary masticatory forces; especially after extraction. Sinus floor augmentation via lateral approach can be performed with different grafting materials. Platelet rich fibrin was found to be effective and safe grafting material; where it stimulates the mitogenic response of the periosteum during the early stage of bone repair. The aim of the study is to evaluate sinus floor augmentation with platelet- rich fibrin as alternative to bone graft versus xenograft with simultaneous implant placement. To fulfill this aim, 20 patients were selected to be medically free to exclude all variable confounders that may affect the wound healing. The residual bone heights were between 4-5 mm. The patients were randomly divided into 2 groups. Where one group received sinus floor augmentation with lateral approach using platelet rich fibrin as grafting material with simultaneous implant placement. While the other group received xenograft as grafting material filling the sinus with simultaneous implant placement. Five months postoperatively, the gain in residual bone height and density were evaluated using CBVT with superimposition technique. When comparing the L-PRF group with xenograft group after 5 months, it was found that mean gain in subsinus height in L-PRF group was 5.167 mm versus 4.075mm in xenograft group after 5 months. There was statistically significant difference between the two groups at P- value 0.038. Also, crestal bone loss in L-PRF group was less than that in xenograft group. Additionally, percentage of density in L-PRF group was 40.214 % versus 28.07 % in xenograft after 5 months. Therefore, percentage of bone density in L-PRF group was more than that in xenograft group by 12.143 %, with statistically significant difference between the two groups at p- value 0.05.