In the aerospace field, some components of rocket engines are solicited under “hydrogen atmosphere”. Under these conditions, the risk of hydrogen embrittlement of these components may be significant. We focused this work on the influence of hydrogen on mechanical behaviors of a nickel-based alloy obtained by Laser Beam Melting. For that, we characterized the microstructure of this material at different scales, and then, we performed several fatigue tests under a hydrogen pressure at room temperature. The obtained results show a reduction of the number of cycles to failure in the presence of hydrogen. This situation is discussed in regard of the interaction between hydrogen and plasticity.