Intranasal polyposis is a chronic inflammatory upper airway disease with unknown aetiology. Interleukin (IL)-4 and IL-8 play very significant roles in allergic events and infectious inflammation, respectively. In contrast, E-selectin is important in the initiation and organization of inflammation. In this study, levels of IL-4, IL-8 and E-selectin were measured in nasal mucosa specimens of intranasal polyposis patients with and without allergic rhinitis, and healthy controls. Healthy controls had significantly higher IL-4 levels than allergic patients and non-allergic patients; IL-4 levels were similar in allergic and non-allergic patients. Allergic and non-allergic patients had significantly higher IL-8 levels than healthy controls; IL-8 levels were comparable in allergic and non-allergic patients. E-selectin levels were similar in all groups. The infection-based theory, represented by IL-8, seems to be more likely than the allergy-based theory, represented by IL-4, for the pathogenesis of nasal polyposis.