The strain induced by substitutional arsenic into the silicon lattice was investigated experimentally. First, a combination of multiple implantations was used to obtain a flat arsenic profile in the first 150 nm of the substrate. Although a full activation of the dopants could be achieved, the EOR defects resulting from the implants were not dissolved and prevented reliable strain measurements. A single implantation was then used. Annealing conditions were carefully chosen to obtain a nearly flat arsenic profile in the first 400 nm of the substrate and to dissolve the EOR defects. Sheet resistance, TEM and RBS measurements confirmed the full activation of the samples and the dissolution of the EOR defects. HRXRD was then used to characterize the strain. The interpretation of the measurements via strain simulation indicated a lattice strain of (-1.5 +/- 0.7)x10(-5) associated with a lattice contraction at a concentration of 2x10(20) cm(-3). This value is significantly lower than the values reported in literature.