The annual glacier mass balance of Hallstätter Gletscher in Austria is measured since 2006-10-01 with the direct glaciological method in the fixed date system (1st October to 30th September of the following year). The accumulation of snow is measured by determination of the water equivalent in 6 snow pits, the ice ablation is measured with 15 stakes drilled into the ice. Results are the annual net mass balance in kg, the total accumulation and ablation, the glacier area and the portions of the area which are subject to ablation and accumulation, the elevation of the equilibrium line and the specific mass balance in kg/m**2 (= mm w.e.). The accumulation during the winter is determined by the 1st May.The project is funded by the Amt der Oberösterreichischen Landesregierung and the Energie AG. The measurements are carried out by the Institute for Interdisciplinary Mountain Research (http://www.mountainresearch.at/index.php/en/) of the Austrian Academy of Sciences and the company Blue Sky in Gmunden, Austria.New data will be added every year.