Material surface state is a key parameter in several fields such as friction or machining. At small scales, surface alteration is also at the roots of major physical phenomena as in catalysis or nanomechanical engineering. In this study, we model the influence of surface roughness on the mechanical response of metallic nanocrystals. After having introduced Pyrough [1], the tool we have recently developed to design virtual samples with rough surfaces, compression simulation of Au nanoparticles with rough surfaces are presented as compared to samples with perfectly flat surfaces [2]. Our results show that surface roughness has a major impact on the mechanical properties and the dislocation microstructure evolution during plastic deformation, as confirmed by statistical analysis performed on hundreds of atomistic simulations. Our results shed new light on the mechanics of nano-objects and on measurement discrepancies commonly observed at small-scale. [1] H. Iteney, J.A.G. Joa, C.L. Bourlot, T.W. Cornelius, O. Thomas, J. Amodeo, Pyrough: A tool to build 3D samples with rough surfaces for atomistic and finite-element simulations, Comput. Phys. Commun. 295 (2024) 108958. https://doi.org/10.1016/j.cpc.2023.108958 [2] H. Iteney, T.W. Cornelius, O. Thomas, J. Amodeo, Influence of surface roughness on the deformation of gold nanoparticles under compression, Acta Mater. 281 (2024) 120317. https://doi.org/10.1016/j.actamat.2024.120317