At1900 the Mödlingbach has been regulated and its natural vegetation was non-existing. In the year 2000 the municipality of Mödling (Lower Austria) started its renaturalization in cooperation with the University of Bodenkultur (University of Natural Resources and Life Sciences, Vienna) and the Provincial Water Administration of Lower Austria. This diploma thesis examines the soil-bioengineering techniques applied at the Mödlingbach and its effects on the structures of the riverbed and on the fish stock. The main goal was to show the implementation of measures concerning the ecological efficiency of the Mödlingbach. The indicators used for the evaluation of the actual development were the riverbed and the composition of substrates. In addition, the fish stock was evaluated. In a first step the condition of the structures and its effects were technically and ecologically analyzed. Afterwards, the cross profiles of the Mödlingbach were detected. Probes of the sediment were gathered and subjected to a sieve analysis. Finally, the fish stock was collected with the help of the local fishery association. As a result, positive ecological effects were recognizable in the river-section under scrutiny. In comparison to the situation before the naturalization the soil-bioengineering techniques led to new natural habitats and living spaces as the development of riffle and pool systems or areas with slow current. Through morphological improvements it was possible to create the conditions for a natural fish stock. Since March 2007 the structures of the river section have evolved positively as some of the used soil-bioengineering techniques showed to be very effective. The structures turn out to be a functioning connection between water and shore. The soil-bioengineering technique serves as a bridge between technical and ecological function.