Freeze-dried platelet-rich plasma (FD PRP) is of potential value for clinical applications. However, growth factors released from FD PRP have not been well studied. Our study investigates growth factor release from FD PRP preparations, compared with other PRP samples, to further facilitate such clinical use. We used four experimental groups: (1) Fresh porcine PRP (PRP), (2) PRP activated by calcium chloride (CaCl2) (Ca PRP), (3) PRP activated by CaCl2, followed by freeze drying (Ca-FD PRP), and (4) PRP freeze-dried first, then activated by CaCl2 (FD-Ca PRP). All FD PRP samples were kept for up to 4 weeks at room temperature (22 °C) and reconstituted prior to analysis. Transforming growth factor-β1 (TGF-β1), platelet-derived growth factor AB (PDGF-AB), and vascular endothelial growth factor (VEGF) were quantitated by ELISA at 15 min and 1 h incubation times. The concentrations of all growth factors in Ca PRP, measured at 1 h, were significantly higher than those in PRP (p < 0.05). PDGF-AB concentrations in FD-Ca PRP were not significantly different than in Ca PRP (p > 0.05). Levels of VEGF in Ca-FD PRP were not significantly different than in Ca PRP (p > 0.05). However, TGF-β1 concentrations in Ca-FD PRP, measured at 15 min, were higher than those in Ca PRP (p < 0.05). PRP was activated efficiently by calcium chloride. Freeze-dried PRP remained rich in growth factors after storage for 4 weeks at room temperature, indicating its ease of use and wider possibilities for clinical applications. This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.