Aerosol therapy with a nebulizer (nebulizer treatment) enables administration of a high drug concentration to the region requiring medication and consequently a reduction of the general side effects. Thus, nebulizer treatment is considered to be safe and effective, and it has often been used for the treatment of inflammatory and allergic diseases of the upper airway. However, the efficacy of nebulizer treatment is not yet clearly understood. Therefore, its efficacy for the upper airway is assessed on the basis of evidence from basic and clinical studies reported so far. Regarding evidence on the value of nebulizer treatment for the upper airway, factors related to local deposition of drug aerosol particles, appropriate antibiotics for nebulizer treatment, efficacy of nebulizer treatment for rhinosinusitis, efficacy of hyperthermic aerosol therapy for allergic rhinitis, efficacy of nebulizer treatment for pharyngitis and laryngitis, and inventions for the increasing efficacy of nebulizer treatment are presented.