Platelet-rich-plasma (PRP) has attracted great attention and has been increasingly used for a variety of clinical applications including orthopaedic surgeries, periodontal and oral surgeries, maxillofacial surgeries, plastic surgeries, and sports medicine. However, very little is known about the antimicrobial activities of PRP. In this study, PRP is found to have antimicrobial properties both in vitro and in vivo. In vitro, the antimicrobial properties of PRP have been found to be bacterial strain specific and time specific: PRP has significantly (80–100 fold reduction in colony forming units) inhibited the growth of methicillin sensitive and methicillin resistant Staphylococcus aureus, Group A streptococcus, and Neisseria gonorrhoeae within the first few hours but it has no significant antimicrobial properties against E. coli and Pseudomonas. The antimicrobial properties of PRP also depend on the concentration of thrombin. In vivo, an implant-associated spinal infection rabbit model has been established and used to evaluate the antimicrobial and wound healing properties of PRP. Compared to the infection controls, PRP treatment has resulted in significant reduction in bacterial colonies in bone samples at all time points studied (i.e. 1, 2, and 3 weeks) and significant increase in mineralized tissues (thereby better bone healing) at post-operative weeks 2 and 3. PRP therefore may be a useful adjunct strategy against post-operative implant-associated infections.