Despite a considerable body of evidence documenting the scientific as well as clinical effectiveness of platelet rich plasma (PRP) in both medicine and dentistry, use of the material remains controversial. A review of the literature provides some insight into the controversy. Most randomized and controlled studies using FDA-cleared PRP processing devices and statistically significant numbers report efficacy of PRP. However, most studies reporting no benefit from PRP can be shown to use either inappropriate animal models, PRP devices that are incapable of processing a concentration of viable platelets, small numbers of subjects, or no controls. Two comprehensive controlled studies will be presented, providing significant evidence to support improved clinical outcomes when PRP is used not only with autogenous grafts but also to varying degrees with all nonviable graft materials.