Atrophic rhinitis (AR) is a chronic disease of the nasal mucosa. The disease is characterized by abnormally wide nasal cavities and its main symptoms are dryness, crusting, atrophy, fetor, and a paradoxical sensation of nasal congestion. The etiology of the disease remains unknown. Here, we propose that excessive mucus evaporation is the basis for the relentless nature of this disease. Airflow and water and heat transport were simulated using computational fluid dynamics (CFD) techniques. The nasal geometry of an AR patient was acquired from computed tomography (CT) scans before and after a procedure to narrow the nasal cavity. Simulations of air conditioning in the AR nose were compared to similar computations performed within the nasal geometries of 4 healthy humans. The excessively wide cavity of the patient generated abnormal flow patterns, which led to abnormal patterns of water fluxes across the wall. Geometrically, the AR nose had a much lower surface area to volume ratio than the healthy cavities, which increased water fluxes per unit area. Nevertheless, the simulations indicated that the atrophic nose did not condition inspired air as effectively as the healthy geometries. These simulations of water transport in the nasal cavity are consistent with the hypothesis that excessive mucus evaporation plays a key role in the pathophysiology of AR. We conclude that the main goals of a surgery to treat atrophic rhinitis should be (i) to restore the original surface area of the nose, (ii) to restore the physiological airflow distribution, and (iii) to create symmetric cavities.