Biodegradable polymeric nanocylinders were fabricated by segmental degradation of electrospun nanofibers. P01Y(L-lactic acid) (PLA) was electrospun to produce non-crystalline nanofibers that were immediately treated with amino group-containing strong bases to fabricate semicrystalline PLA nanocylinders with tunable aspect ratio. The formation of PLA nanocylinders was attributed to two concurrent events occurring during the aminolysis reaction: (i) development of stacked lamellae and (ii) transversely oriented degradation and fragmentation of the amorphous gaps between lamellae, both responsible for -1, the fragmentation of PLA nanofibers into uniformly shaped nanocylinders. The aspect ratio of PLA nanocylinders was tunable by varying aminolysis time and controlling nanofiber diameter.