Rockfall barriers are optimized to absorb high punctual impact energies. In mountain areas the barriers are also loaded by avalanches and snow pressure. Snowpack forces and dynamic avalanche pressures act over a much larger area and over longer time periods. Thus, if not properly designed, rockfall barriers can be damaged. In winter 2003-2006 we investigated the interaction of flexible rockfall barriers with avalanches and snow pressure on a study site in Fieberbrunn, Austria and in other areas. In several locations the barriers successfully stopped small wet snow avalanches. However, the main problem turned out to be the insufficient retention capacity during the whole winter and the structural behaviour. The weakest points are the retaining ropes and the post foundations. For an appropriate design of the barrier the main input factors determining snow pressure and avalanche pressure have to be assessed.