In June 2011, a first attempt for measuring bedload transport in the main channel of an alpine river, the Arc en Maurienne River, was undertaken contemporaneously deploying bedload samplers and hydrophones. The Ehrenberger type bedload basket sampler was unstable at high velocities. Samples were successively taken using a large (152 mm) Helley-Smith type bedload sampler. The considerable temporal variability of bedload flux based on H-S sampling contradicts the generally steady hydrophone signals. The position of the sampler on the river bed may have likely been uneven due to the presence of boulders, thereby decreasing sampler catch in some instances. Apparently when the sampler was evenly set on the riverbed, its efficiency decreased due to the presence of organic matter and large concentration of suspended sediments. A simple hydraulic model was applied to estimate the variation of water depth, velocity and bedload discharge with water discharge, yielding consistent results compared to measured water depths and velocities. The calculated bedload discharge using classical formulae is, however, larger than the average monitored, confirming the relatively low efficiency of the bedload sampler.