Objective To investigate the morphol. ultrastructure of platelet rich fibrin (PRF) and its implication. Methods PRF was prepared from venous blood samples from 10 healthy donors. The PRF was observed by light microscopy (H-E staining and Wright Giemsa staining), SEM (SEM) and transmission electron microscopy (TEM), resp. Results PRF presentedas light yellow fibrin gel. HE staining showed that collagen fiber was of uniform and light red networkstructure. In the near cell end, the fibers were denser and contained lots of platelets. Giemsa staining showed that the collagen fibers were of light blue mesh structure, and the dark blue white blood cells were in the near cell end. SEM observation found that collagen fibers were arranged in a porous reticular scaffold, containing a large number of static or protruding platelets and leukocytes. TEM showed that platelets were at rest or activated, α-particles were released between platelets or fibers, which displayed ahigh d. area between cells. Conclusion Through the reticular stereoscopic structure of collagen fibers and rich platelets activating growth factor release, PRF plays an important biol. role.