The objectives of this study were to observe the lectin-binding patterns of endothelial cells of murine respiratory and olfactory mucosa and to find the marker pectin differentiating fenestrated from continuous vessels on light microscopy. Twelve BALB/C mice were fixed with 10% buffered formalin and embedded in paraffin. Serial sections, 4 μm in thickness, were made and stained with sialic acid-specific pectins (WGA, MAA, SNA) and sialic acid-nonspecific pectins (RCA-I, DBA, GSI-B4, UEA-I, SBA, PNA, Con-A) using the avidin-biotin peroxidase method. Diamlnobenzidine was used as a chromogen. The slides were counterstained with the Mayer's hematoxylin. pectin-binding patterns were observed using Vanox-S light microscope. WGA and RCA-I were labelled on respiratory and olfactory mucosa irrespective of the type of blood vessel but the binding patterns with WGA were inhomogeneous. These results suggest that N-acetrlglucosamine, sialic acid, N-acetylgalactosamine, and galactose exist In endothelial surface of murine nasal mucosa. But we could not find the marker lectin which differentiates continuous from fenestrated vessels. Further study using the Lowicryl K4M-embedding method and immunoelectromicroscopy will be required.