Nasal breathing is completely ceased after total laryngectomy. This results in some structural changes in the nasal mucosa, which has been described in numerous studies. This study investigates the changes that appear in the paranasal sinus mucosa. Eight patients who had undergone total laryngectomy at least 1-year ago were enrolled. Under general anesthesia, maxillary sinuses were examined with an endoscope inserted through canine fossa. 1-2 mm mucosal tissues for biopsy were taken from posterior wall of the maxillary sinus. Specimens were evaluated under an electron microscope. Control tissues for biopsy were obtained from two patients who had been operated for other reasons and analyzed under transmission electron microscopy. Results showed that in the control specimens, the epithelial cells appeared normal under transmission electron microscopy. Samples taken from two larygectomees in their first postoperative year were also completely normal. Samples from other larygectomees demonstrated ciliary loss, abundant degenerative vacuoles in ciliated epithelial cells and detachments in the interepithelial junctional complexes. The intracellular respiratory mechanisms such as the mitochondria, golgi complex and endoplasmic reticulum cisternae, and the integrity of the cellular or the nuclear membrane were spared. We conclude that the cessation of nasal breathing resulted in degenerative changes that could be reversible in the transmission electron microscopic examination of maxillary sinus mucosa. These changes emerged after 2 years following total laryngectomy. Nevertheless, these changes did not have any negative influence on the clinical outcome in this group of patients.