Background: Oral implants require adequate bone support, which is often facilitated by bone augmentation when bone volume is insufficient. Autogenous bone (AB) has been considered the 'gold standard' for such procedures due to its osteogenic properties, but it necessitates a second surgical site, which increases patient morbidity. Trial Design and Methods: This study was a randomized, double-blind, split-mouth clinical trial comparing L PRF (leukocyte-platelet rich fibrin) bone-block grafts against a composite graft mixture of 50% AB with 50% deproteinized bovine bone mineral (DBBM) for vertical guided bone regeneration (GBR). The trial included 6 patients needing bilateral vertical GBR before implant placement. A dense polytetrafluoroethylene (d-PTFE) membrane was used for both test and control sites. The primary outcome measure was vertical bone height (VBH) gain, assessed via cone beam computed tomography (CBCT) at 9 and 25 months post-operation. Results: There was no significant difference in VBH gain between the test and control sites at any time points, with a mean VBH gain at implant placement of 4.6 ± 3.0 mm for test sites and 5.2 ± 2.7 mm for control sites. At 1 year after loading of the implants the VBH gain was 3.0 ± 2.8 mm for test sites and 3.8 ± 2.6 mm for control sites (P value 0.96). Complications were minimal and included one implant loss due to infection in a test site. Conclusions: The L-PRF bone block could be a viable alternative to the composite graft, potentially reducing the need for harvesting bone from a second surgical site. Future studies with larger sample sizes are needed to confirm these findings and to explore the biological benefits of integrating the L-PRF bone-block into bone graft materials for oral implantology.