Paraffin-embedded human bronchial biopsies, obtained in macroscopically healthy areas, were examined using nine peroxidase-bound lectins. These were either isolated or purified by affinity column chromatography (Ulex europeus, Triticum vulgare, Glycine max, and Arachis hypogatea lectins) or commercial preparations (Lotus tetragonolobus, Canavalia ensiformis, Helix pomatia, Phaseolus vulgaris, and Lens culinaris lectins) and conjugated to peroxidase (except for concanavalin A). These labeled lectins were used as specific molecular probes to localize differences in carbohydrate-containing components present in the different types of glandular cells of human bronchial mucosa. The choice of fixative was crucial and tests used for this study have shown that Carnoy's solution seems to be the most appropriate solution to preserve mucous glycoproteins in situ. Comparison of the affinity of several lectins for human bronchial glycoproteins and for bronchial mucosa demonstrates the predominance of serum-type glycoproteins in serous cells of the submucosal glands and mucin-type glycoproteins in mucous cells of the submucosal glands and in goblet cells of the bronchial epithelium. Furthermore the data obtained with some lectins, such as Helix pomatia agglutinin, suggest that there are some differences in the mucins synthesized by goblet cells and by mucous cells.