Crystalline nanorods composed of 9-anthracene carboxylic acid (9-AC) are synthesized using nanoporous Al2O3 templates. When a segment of an isolated rod is exposed to UV-light, localized solid-state photodimerization of the 9-AC molecules induces micrometer-scale bending (see figure). The nanorod reverts back to its original shape after several minutes in the dark at room temperature. The reversible photoinduced shape change could be repeated multiple times.