This study was conducted on species composition, morphology, ecological characteristics, biotope distribution, ecological groups, biodiversity indicators and zoogeography of leeches and gastropods distributed in the lower Ak-Buura River. According to the results, it was found that 7 species of leeches belonging to 4 families and 6 genera and 10 species of fresh-water gastropods belonging to 3 families and 6 genera live in the lower Ak-Buura River. In the river, it was observed that leeches are mainly distributed in muddy biotopes, and gastropods are widespread in muddy, stony and sandy biotopes with a lot of plants. Biodiversity indices of leeches and gastropods in the Ak-Buura River were analyzed using the Shannon index. As a result, it was determined that the biodiversity index of the Ak-Buura river is lower than other rivers in the Fergana valley (H' = 0.81-1.17). This is mainly due to the eutrophication of some parts of the river and the instability of the water hydro-regime. Most of the leeches distributed in the river are carnivores, and gastropods are phytophages. According to the zoogeographical analysis, it was found that leeches are Holarctic, Palearctic, Western Palearctic, and gastropods are composed of European-Siberian, Palearctic and Central Asian species.
