The paper presents some results of the 2006 Sava survey. The investigation was carried out at four locations along 188 km of the Serbian stretch of the Sava River (206 km of the river belongs to Serbia). Among other things (physical and chemical properties of water and sediment, phytoplankton, and phytobenthos), the study included investigation of aquatic macroinvertebrates. Sixty-two taxa were identified in this typical lowland river. Mollusks and oligochaetes were the most diverse groups of macroinvertebrates. Our results support the hypothesis that the Sava River is an important bio-invasion trajectory, a part of the Southern Invasive Corridor of Europe. Five alien macroinvertebrate taxa were identified, some of which (Corbicula fluminea, Branchyura sowerbyi, and Anodonta woodiana) were found to be important components of the community.