The Balikdami Wetland, an impoundment of the upper course of the Sakarya River located near Sivrihisar (Eskisehir, Central Anatolia), is one of the most important bird conservation areas in Turkey. This area also encompasses the mouth of the torrential Goksu Stream, which is partly hyporheic. During this study ( 2001 - 2003), 1,471 specimens representing 34 taxa of aquatic Oligochaeta were collected from the Balikdami Wetland. All the species identified are new records for Balikdami. Two species, Coralliodrilus amissus sp. n. and Gianius anatolicus sp. n., are new to science, and five species, Stylodrilus parvus (Hrabe et Cernosvitov, 1927), Chaetogaster diastrophus (Gruithuisen, 1828), Peipsidrilus libanus ( Giani et al., 1982), Tubifex acuticularis Martinez-Ansemil et Giani, 1983, and Epirodrilus moubayedi Giani et Martinez- Ansemil, 1983, are new records for Turkey. Two other species, Peipsidrilus libanus and Tubifex acuticularis, are re-described. The oligochaete fauna of the wetland was dominated by widely distributed tubificid taxa. The lumbriculid Stylodrilus parvus was the most abundant species in the Goksu stream. The two new phallodriline species are remarkable since most representatives of this subfamily live in the marine environment. Due to the species richness and diversity of Oligochaeta, as well as of several other animal groups, the Balikdami wetland area deserves conservation.