In this research, we have employed molecular dynamics (MD) simulations to computationally explore the effects of hydrostatic stress on the shear deformation behavior of nanocrystalline (NC) Cu, over a range of grain size (5–20 nm) and temperature (10–500 K). Simulated nanocrystals were deformed under shear with superimposed isotropic tensile/compressive hydrostatic stress of magnitude up to 5 GPa. The results suggest that the shear strength increases under imposed compressive , and decreases under imposed tensile , by around 0.05–0.09 GPa for every GPa of imposed hydrostatic pressure. At 300 K, we computed activation volumes (3.5–9 b3) and activation energies (0.2–0.3 eV), with values agreeing with those reported in previous experimental and theoretical work, notwithstanding the extreme deformation rates imposed in MD simulations. Additionally, we observed that shear deformation under an imposed compressive hydrostatic stress tends to slightly increase both the activation volumes and the energy activation barrier. Finally, no discernible pressure effect could be observed on the distribution of inelastic shear strain.