In situ stress measurements have been performed during the deposition of epitaxial Ag monolayers on a Fe whisker. A compressive stress of -0.6 GPa is measured above a 5-ML Ag thickness which is ascribed to the epitaxial misfit of -0.8% between Ag and Fe. Back-extrapolation of the coverage dependent stress measurements to zero coverage reveals an Ag-induced change of the surface stress of Fe(100) of -1.23 N/m. Comparing this surface stress change with the calculated surface stress for Ag(100) suggests a tensile surface stress of +2.05 N/m for clean Fe(100). The deposition of 2-5 layers of Ag does not change the stress induced by the first layer significantly. This almost stress free growth is assigned to a rougher surface morphology which is most likely caused by a surface alloy formation.