The extended defects in polycrystalline CdTe thin films grown by close-spaced sublimation are characterized by means of high-resolution transmission electron microscopy. We found that the extended defects are mostly lamellar twins and intrinsic and extrinsic stacking faults. The stacking faults always propagate across the grains without ending at a partial dislocation inside the grains. The atomic structures of the defects are confirmed.