Nasal cytology represents a valid method in the differential diagnosis of allergic and non-allergic nasal diseases, as it is simple, safe, non-invasive, cost-effective, and easy to perform both in the medical and paediatric office. In particular, through cytological investigation it is possible to diagnose a group of non-allergic infective rhinitis that still today constitutes a vague aspect of the clinical-diagnostic-therapeutic approach to eosinophilic non-allergic rhinitis (NARES), non-allergic rhinitis mast cell (NARMA), neutrophilic non-allergic rhinitis (NARNA), and eosinophil-mast cell non-allergic rhinitis (NARESMA). Preventive treatment of nasal diseases, when guided by rhinocytograms, leads to a favorable clinical and time-dependent outcome. These advantages are reflected in a better quality of life and in a reduction in National Health Service costs, without chronic evolution of the disease to complications.