Atomistic computer simulations are used to study the zero-temperature interaction between steps in vicinal free fcc surfaces in order to test the continuum-elastic theory of Marchenko and Parshin (MP). Two different types of surface steps, both parallel to 〈001〉 but situated, respectively, on the (100) and (110) planes, are investigated using two qualitatively different interatomic potentials, one of the embedded-atom-method type and the other the Lennard-Jones potential. In agreement with the MP theory, for the largest step separations δ the energy due to the step-step repulsion is found to decrease as δ−2, with a strength given by the surface-stess tensor and the elastic moduli of the material. Surprisingly, for both potentials and for both types of steps the δ−2 power law appears to be obeyed even for the smallest step separations, albeit with a 2–3 times smaller interaction strength. The relationship of our simulation results with a nearest-neighbor broken-bond model is also explored.