Aquatic oligochaetes were investigated from a small amount of sediment sampled from the Jung-nang Stream, an urban stream in Seoul, Korea, in November 2012. Sorted oligochaetes were observed under alight microscope in a drop of carbonated water, and then preserved in 70% ethanol. Some specimens were slidemounted using glycerin and Eupharal. As a result, the following 12 species were identified including 8 newKorean records, Bothrioneurum vejdoskyanumStolc, Branchiodrilus hortensis(Stephenson), ChaetogastercristalinusVejdosky, Nais communisPiguet, Nais pardalisPiguet, Dero obtusad’Udekem, PiguetielladenticulataLiang, and Haemonais waldvogeli Brescher and 4 additional known species, Limnodrilus hoffmeisteriCleparéde, Branchiura sowerbyi Beddard, Chaetogaster diastrophus(Gruithuisen), and Stylaria fossularisLeidy.This study shows how freshwater oligochaetes are diverse even in urban streams in Korea, if a propersamplingand examining method is employed.