Purpose: The purpose of this study was to evaluate the combination of anorganic bovine bone allograft (ABB) with platelet-rich plasma (PRP) when used in vertical bone augmentation. Materials and Methods: Sixteen healthy 6-month-old female New Zealand rabbits were used in this study. Rabbits were randomly divided into two groups of eight animals each. Created calvarial defects were grafted with ABB or PRP in the first group whereas, in the second group, one cylinder was filled with PRP+ABB and the contralateral cylinder was left ungrafted to be filled by autologous blood (control cylinder). Six weeks after intervention, animals were sacrificed and biopsies were taken. Densitometric, histologic, and histomorphometric analyses were performed to evaluate bone mineral density, vertical bone augmentation, and remaining graft volume, respectively. Statistical analyses were performed with the Mann-Whitney test, using a significance level of P .05. Results: Six weeks after rabbit calvariae were augmented, data analysis revealed that the mixture of PRP and ABB produced twice the vertical bone volume of ABB alone (P .0001). Conclusion: Based upon this study of 16 rabbits, it appears that the combination of ABB with PRP resulted in increased vertical bone augmentation when compared with autologous blood in similarly sized created defects. Keywords: anorganic bovine bone, platelet-rich plasma, titanium cylinder, vertical bone regeneration