Purpose: To investigate the effects of submucosal platelet-rich plasma (PRP) injection on nasal mucosal wound healing after endoscopic sinus surgery. Methods: 24 New Zealand white rabbits were randomly divided into three groups. To mimic surgery, injury was created using 3-mm punch forceps on ventral turbinate mucosa for all groups. Submucosal PRP was injected to the damaged mucosa in the first group (PRP group, n = 8), where 0.9% saline solution to the second group (saline group, n = 8) and no injection to the third one (control group, n = 8). All the animals were sacrificed 14 days after surgery; histopathological examination and hydroxyproline measurements were performed on the mucosa of all groups. Results: Neutrophils, goblet cells, and collagen intensity were found significantly lower (p < 0.05) in PRP group than the control group. Also, the number of ciliary and goblet cells, and collagen intensity were found significantly lower (p < 0.05) in PRP group, than the saline group. In PRP group, hydroxyproline levels were found (p < 0.05) significantly lower than the saline and the control group, and no significant difference was found between the saline group and the control group (p > 0.05). Conclusion: There are many studies in literature showing the positive effects of PRP on wound healing. The results of this study also demonstrated positive effects of PRP on the nasal mucosa. According to these results, PRP injection to the injured nasal mucosa showed anti-inflammatory, mucus-softening, and synechia-reducing effects. Therefore, submucosal PRP injection after endonasal surgeries can be considered an effective application for maintaining nasal physiology.