The elastic strain limit of polycrystalline mixed AgClxBr1−xfibers was studied. These fibers are useful as flexible infrared optical fibers, and the elastic bending regime is preferred for applications which require many bending cycles. The experimental method was based on the spring‐back upon releasing a stressed material, and used specifically calculated expressions. Elastic strain limit values are in the range of 0.15%–0.4%. They depend on composition going through a maximum at around the AgCl0.5Br0.5composition. The dependence on composition is explained by a theoretical model, which is based on a solid‐solution internal stress field, and uses material constants.