Energetics for the chlorination process of Si(100)-(2x1) surfaces with an A-type single step edge were investigated under strain conditions. Strains applied uniaxially in the direction parallel to the exposed surfaces produced little or no effect on the energetics of the first chlorination step leading to fully Cl-covered terraces (one Cl attached to every exposed Si atom). The energy of the second chlorination step (leading to the formation of attached -SiCl2 units) taking place near a step-edge site. however, is affected considerably by the applied strain. The effect was found to be largest for strains applied in the direction perpendicular to the step edge.