The aim of our work is to evaluate the effect of Mitomycin C on the nasal mucosa both clinically and histopathologicaly and comparing these tocontrol cases and to show the possible side effects on the mucosa and mucociliary function. The evaluation will include the ease of use, assessment of results after a period of no less than 6 months postoperatively and if it is worth using routinely. The clinical part included FESS and DCR procedures with application of adjuvant topical 0.4mg/ml MMC solution for 5 minutes, results were compared to control cases. The experimental part included the application of topical 0.4mg/ml MMC solution for 5 minutes on rabbits maxillary sinus antrostomys (unilaterally), while the other side acted as control. Results were analyzed after sacrification regarding the size of the healed ostium as well as examination of the mucosa using Light and Transmission electron microscopy to detect microscopic antiproliferative and adverse effects. The antiproliferative effect of MMC on fibroblasts has been well proven. The results should suggest that the delay in fibrous tissue formation allows healing to occur before scar formation. MMC allows return of normal epithelium & does not cause permanent damage to the mucosa. The cytocidal effect decreases with time shows reversibility, this is proven by the ciliary response as well as the disappearance of dilated smooth endoplasmic reticulum, swollen mitochondria of epithelial cells, intercellular oedema and the presence of intact basal lamina.