Background: The topical application of mitomycin C has been evaluated as a complementary therapy for eosinophilic nasal polyposis (ENP). However, the mechanism underlying the additional benefits of mitomycin C for the control of eosinophilic inflammation and prevention of posttherapeutic relapse remains to be elucidated. In this work, the aim was to characterize the gene expression profile by quantitative real-time polymerase chain reaction (qPCR) of proinflammatory and regulatory biomarkers that are typically associated with ENP and to assess the impact of the topical application of mitomycin C on the nasal mucosal tissue immunologic milieu after ENP surgery. Methods: We have selected 20 patients with ENP that were recommended to undergo surgical intervention. Normal mucosal tissue was obtained from healthy nasal mucosa from six patients with absence of eosinophilic infiltration. To test the effect of mitomycin C, one side of the maxillary sinus mucosa was selected for topical application of this drug and the other received no further treatment and acted as the control. The genes interleukin-4 (IL-4), IL-5, IL-10, IL-13, chemokine (C-C motif) ligand 5 (CCL5), CCL24, colony-stimulating factor 2 (CSF2), transforming growth factor beta 1 (TGFB1), tumor necrosis factor alpha (TNF-alpha), and beta actin (ACTB) were selected for gene expression analysis by qPCR. Results: The data showed higher expression of proinflammatory biomarkers and lower levels of regulatory TGFB1 transcripts in ENP mucosal tissue. Surgery with topical application of mitomycin C induced a prominent transcriptional down-regulation of the immunologic biomarkers, CCL24, TNF-alpha, CSF2, and IL-5, in ENP mucosal tissue. Additionally, this treatment restored the levels of chemokines and cytokines to those observed in the nasal mucosal tissue of control subjects, except for TGFB1, which remained below the reference pattern. Moreover, CSF2 was identified as a putative biomarker with significant predictive value for complementary prophylactic purposes after surgery in ENP patients. Conclusion: After the characterization of the expression signatures of immunologic biomarkers in ENP, we observed that the topical use of mitomycin C is important for the reestablishment of the immunologic microenvironment of a normal expression profile of biomarkers involved in ENP mucosal tissue