Allergic diseases are characterized by allergic complaints in the shock organ and specific immunoglobulin (Ig)E in serum. Literature data indicate that the nasal mucosa itself could produce at least a large part of the specific IgE in allergic rhinitis patients. In order to investigate this hypothesis, nasal mucosal biopsies from the inferior turbinate were taken from symptomatic grass pollen allergic rhinitis patients, symptomatic house dust mite allergic rhinitis patients and nonallergic healthy controls, confirmed by radioallergosorbent test and skin-prick test. Immunohistochemical double-staining was performed for B-cells (CD19) with IgE, plasma cells (CD138) with IgE and plasma cells with biotinylated allergens. Significantly more IgE-positive B-cells and IgE-positive plasma cells were found in the nasal mucosa of allergic patients than in that of nonallergic controls. Double staining with biotinylated allergens and plasma cells showed allergen-positive plasma cells in the nasal mucosa of allergic patients and no allergen-positive plasma cells in the nasal mucosa of nonallergic patients. Blocking experiments using polyclonal antibodies directed against IgE showed a significant reduction in the number of allergen-positive cells in contrast to experiments using polyclonal antibodies directed against IgG, IgA or IgM. This study describes new evidence that specific immunoglobulin E is produced locally in the nasal mucosa in patients with seasonal allergic rhinitis and perennial allergic rhinitis, but not in nonallergic controls.