The methodological approach used in this study is to characterize the number, the density and the diameter distribution of myelinated fibers (MFs) and unmyelinated fibers (UMFs) in sciatic nerve and its main branches of pigeon. The results have shown that the fiber composition is quite variable because in pigeon there are relatively MF with thin myelin sheaths and MF with thicker sheaths. Our data suggest that morphometric analysis could represent a helpful methodological approach to better characterize these systems.