Although rhinitis has been classified as being either allergic, noninfectious, or ‘‘other forms’’ (nonallergic noninfectious), these categories lack strict classification criteria and often overlap. The term ‘‘nonallergic noninfectious rhinitis’’ is commonly applied to a diagnosis of any nasal condition, in which the symptoms are similar to those seen in allergic rhinitis but an allergic aetiology has been excluded. This group comprises several subgroups with ill-defined pathomechanisms, and includes idiopathic rhinitis, irritative-toxic (occupational) rhinitis, hormonal rhinitis, drug-induced rhinitis, and other forms (non-allergic rhinitis with eosinophilia syndrome [NARES], rhinitis due to physical and chemical factors, food-induced rhinitis, emotion-induced rhinitis, atrophic rhinitis). Unlike allergic rhinitis, there are no specific diagnostic tests and diagnosis is primarily based on a history of reaction to specific irritant-toxic triggering agents (either general or occupational), drugs, infections, and hormonal status, coupled with exclusion of allergic rhinitis and other forms of non-allergic rhinitis by skin prick testing. Accordingly, from a clinical standpoint NARES, irritative-toxic, hormonal, drug-induced and idiopathic rhinitis are possibly the least difficult forms of nonallergic rhinitis to diagnose.