Samples of aquatic oligochaetes were collected from sediments of 10 sites along the middle sector of River Tigris / Iraq for a period from November 2018 to December 2019. Species of tubificid worms (subfamily Tubificinae ) were morphologically identified from a total collection of 7556 specimens, with Limnodrilus spp as the most abundant species ( 74% of the total individuals), especially L. hoffmeisteri Claparède,1862, and L claparedianus, Ratzel,1868, in addition to individuals of  L. cervix Brinkhurst, 1963 ,  and L. udekemianus Claparède 1862. Other tubificid worms, with hair chaetae were identified as Aulodrilus pigueti Kowalewski,1914; Embolocephalus velutinus (Grube, 1879) ; Potamothrix bavaricus (Őschmann, 1913) and  P. hammoniensis Michaelsen 1910.; Psammoryctides albicola ( Michaelsen, 1901); P. barbatus (Grube,1891); P. moravicus (Hrabě, 1934); and Tubifex tubifex (Müller, 1774).Two species of the subfamily Rhyacodrillinae, were also identified as Branchiura sowerbyi Beddard, 1892, and Rhyacodrilus coccineus (Vejddovský, 1875), and two species of the subfamily Naidinae, Amphichaeta leydigii Tauber, 1879, and Slavina appendiculata (d' Udekem, 1855), in addition to Pristina sima (Marcus, 1944) (subfamily Pristininae). Hemifridericia sp. (Nielsen & Christensen, 1959) of the family Enchytraeidae was recorded from one site only during November, and identified by conserved 18s rRNA encoding gene sequence. The query sequence was 96.13% identical to Hemifridericia parva Nielsen & Christensen, 1959.