ABSTRACT PURPOSE: To investigate if the association of fat grafts and platelet-rich plasma (PRP) improves graft viability in female rats. METHODS: This is an experimental, randomized and blinded study, which involved 47 rats. Fat was harvested from the inguinal region and grafted to the cranial region. The experimental group consisted of PRP-enriched fat grafts (n=22) whilst the control group consisted of fat graft only (n=25). After a 100-day period, the animals were euthanised and the fat grafts were analyzed using scores from 0 (absent) to 4 (abundant), in optical microscopy by two independent and blinded pathologists. RESULTS: Regarding fat graft cell viability, the PRP group scored moderate/abundant in 63% of cases and the fat graft only group scored absent/slight in 72% of cases (p=0.03). The PRP group also presented lower fat necrosis scores when compared to the fat graft only group (p=0.03). Tumors (dermoid cysts) within the fat grafts were observed in three animals in which the grafts were mixed with PRP. CONCLUSION: Platelet-rich plasma improves the viability and integration of fat grafts in rats, but more studies are needed to fully understand the exact mechanisms that lead to this improvement and assess the safety of the method for use in humans.