The effective elastic stiffnesses C11, C12 and C44 of InAs and derived elastic constants are determined for states of uniform volumetric strain by atomistic simulation. The effective elastic stiffnesses C11 and C12 are found to increase significantly with strain whereas C44 is found to be nearly independent of strain. Results for the bulk modulus are consistent with high-pressure experiments and nonlinear elasticity theories. The effective Young’s modulus is found to be nearly independent of strain whereas the effective Poisson’s ratio increases by about 40% over the range 0%–20% volumetric strain. The use of effective elastic stiffnesses within the isotropic approximation leads to a hydrostatic strain for an InAs quantum dot which is 16% smaller than the uncorrected value. It is concluded that continuum techniques for calculating quantum-dot-induced strain in the InAs/GaAs system should include strain-dependent InAs elastic stiffnesses for maximum accuracy. © 2002 American Institute of Physics.