Electrochemically deposited Pd-induced crystallization of prepatterned amorphous silicon (a-Si) thin films was proposed for the first time in this study. Most of palladium clusters were found to deposit on the sidewall of the amorphous-silicon islands. After samples were annealed at 530degreesC, parallel needlelike polycrystalline silicon grains were observed on the a-Si film with a constant angle of similar to55degrees from the edge. The direction of the primary grain growth was along [211] and the secondary growth occurred along [011] direction.