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The resistance dislocation loops provide to the glide of dislocations is an important element of several features of plasticity of irradiated metals. In the present work, a dislocation dynamics model based on the elasticity treatment of dislocations, with self-stress effects included, has been used to investigate the critical applied stress required for a gliding dislocation to overcome the stress field of a row of sessile loops near the glide plane. The critical stress has been determined for wide ranges of loop size, spacing and distance from the glide plane. Various approximations to the loop distribution have been tested, including an edge dipole, a single dislocation and a row of infinitesimal loops. The infinitesimal loop model, in particular, is shown to give good agreement with the accurate simulation data over a wide range of loop size and spacing. The ranges of applicability are discussed and compared with previous treatments in which such approximations have been used to investigate hardening due to dislocation–loop interactions.