Objective · To compare the difference of the regeneration capacity of tissue in root canals between concentrated growth factor (CGF) and blood clot by animal study. Methods · CGF was prepared from the upper arm venous blood of healthy volunteers. CGF was implanted into the root segments of isolated teeth, which is the experimental group, and the whole blood was injected into the root segments to form blood clots, which is the control group, with 18 samples in each group. The samples of the control group and experimental group were injected subcutaneously on both sides of the back of nude mice, respectively, and were taken out 4 and 6 weeks after transplantation. Hematoxylin and eosin staining (H-E staining) was used to observe the structure of newly formed tissue in root canals and calculate its area proportion. Immunohistochemical analysis, immunofluorescence analysis and modified Masson staining were used to detect the components of the newly formed tissue, and the area ratio and microvessel density of each component were calculated. Results · The structure of the newly formed tissue induced by the two groups was similar, and the main components were collagen fibers, blood vessels, nerve fibers and adipose tissue. After 4 and 6 weeks of implantation, compared with the control group, the proportion of the newly formed tissue area and microvessel density in the experimental group were higher (all P<0.05). After 6 weeks of implantation, compared with the control group, the proportion of new nerve fibers in the experimental group was increased (P=0.047). Conclusion · CGF and blood clot-induced endodontic tissue regeneration ability is similar, which may imply that CGF can be an alternative to blood clot in the regenerative endodontic treatment.