Wallerian degeneration of the cerebral peduncle is a common MRI finding after cerebral injury. The degree of peduncular atrophy reflects the extent of damage in the corticospinal tract. The acute phase of Wallerian degeneration is visible with Diffusion-Weighted-Imaging. New investigation with Diffusion-Tensor-Imaging quantifies Wallerian degeneration in the subacute ischemic phase and is a good predictor for later functional recovery after stroke.