The rolling, recrystallization and cooling of AgCl containing 1–5μm glass spheres generates thermal misfit dislocations. Under stress, prismatic loops elongate in the glide cylinder defined by their line sense and Burgers vector. Using optical microscopy, the shape of dislocation loops under an applied stress of 2.3MPa is measured. The measurements are corrected for a friction stress of 0.34MPa and compared with a model which incorporates the orientation dependent line tension (ODLT) of a dislocation. The measured data show considerable scatter; after averaging, good agreement between theory and experiment is obtained.