This thesis describes the research conducted on three stations in the area of the Grab river, which belongs to the left tributary of the river Cetina and belongs to the karst rivers of southern Dalmatia. The conducted research included the determination of physico-chemical parameters and the collection of macrozoobenthos. Physico-chemical parameters are determined using standard physicochemical methods and are in line with expectations. A qualitative sample of macrozoobenthos was collected from three stations along the river. Macrozoobenthos samples determined the Illyrian biotic index according to which the water quality of the Grab river was determined.