By the presence of dislocations the channels in a single crystal are distorted. The distortion modifies the motion in planar channels, and the extent to which the modified motion influences energy loss spectra of ions transmitted through thin single crystals with screw-dislocations is examined. In the calculation the stopping power model of Robinson1is used, and the motion of the ions in the distorted channels is solved approximately. Within the model used it is concluded that the presence of dislocations will be hard to detect using only energy loss measurements.