Objective To investigate the role of platelet rich plasma (PRP) on free fat graft's survival in a rat model.Methods Twenty-four rats were used in the experiment.For each rat,three groups of free fat grafts were injected into the subcutaneous layer of dorsum.Group A was the control group with 0.5 ml fat and 0.12 ml normal saline.Group B received 0.5 ml fat and 0.1 ml PRP with 0.02 ml normal saline.Group C was given combination of 0.5 ml fat and 0.1 ml PRP which was activated by 0.02 ml calcium chloride.Eight rats were euthanised using pentobarbital sodium each time,1,2 and 3 months after fat transplantation.Specimens were acquired and stained with haematoxylineeosin,and then the histological changes examined using light microscopy.All the data were statistically analysed using paired t test to determine if there were differences between the study groups.Results Compared the volume of the fat grafts at 1 month,there was no deference between the groups(P＞0.05).However,the diameter of group C was significantly higher than group A (P＜0.05).On histological examination,larger vascular density was observed in group C compared with group A at 1 month (P＜0.05).And reduced inflammatory reaction was also observed in group C at 3 months(P＜0.05).While other histological parameters were not statistically significant (P＞0.05).Conclusions PRP does not enhance the survival of fat graft in the Wistar rat model.