Secretory activity in the glands of the nasal polyps from 15 patients with or without allergic histories was examined by using a direct (anti-IgA) or indirect (anti-SC) immunofluorescent technique. Glands were found in all the examined nasal polyps, but in many, only a few were present. Active secretory process of IgA was observed in the intraepithelial glands of the ciliated, pseudostratified epithelium and in some of the glandular ductules lined with simple, cuboidal epithelium. Most of the dilated glandular ductules, on the contrary, appeared to be lacking in secretory activity of IgA. Such were commonly filled with mucus materials and their epithelial glandular cells showed no fluorescence for anti-SC, whereas the active IgA secreting cells showed a heavy fluorescence for secretory component (SC) in indirect immunofluorescent studies. Activity of the glandular ductules, therefore, was determined by examining the SC producing activity. In some extracted polyps, SC containing dilated glands were present. These active glands, however, lost the SC producing activity followed by the stasis of mucus flow in the lumen. Thus, when the glands were occupied by mucus materials, stretched and cystic degeneration ensued.