The morphology and morphometry of the olfactory organ of Korean torrent catfishes, genus Liobagrus, consisting of only five endemic species, were investigated by stereo microscopy, scanning electron microscopy, and statistical analysis. They showed the same morphological structure, externally and internally, including a tubular anterior nostril, a slit posterior nostril, and a rosette structure with several linguiform lamellae. Interestingly, however, the lamellar number (LN) revealed specific characteristics useful to identify the five species anatomically: 16-19 in Liobagrus andersoni (with standard length, SL, 96.8 ± 5.5 mm, mean ± SD), 14-16 in Liobagrus obesus (86.9 ± 13.4 mm), 22-27 in Liobagrus mediadiposalis (99.8
Keywords: lamellar number; micro-habitat adaptation; olfactory structure; ratio; standard length; taxonomic character.