Object. The purpose of this study was to examine whether choline acetyl transferase (ChAT) staining can be used for assessing the rate of motor neuron regeneration at an early phase of axon outgrowth. Methods. The authors developed a new sciatic nerve crush model in adult mice. In this model, in addition to performing a sciatic nerve crush injury, the authors excised the ipsilateral lumbar L3-6 dorsal root ganglion (DRG), which resulted in degeneration of the sensory fibers entering into the sciatic nerve. Crushed nerve sections obtained at Day 3 or Day 7 postinjury were analyzed by means of immunostaining. Results. The immunostaining showed that ChAT, a motor axon-specific antigen, was totally co-localized with growth-associated protein 43 (GAP-43), which is expressed in regenerating nerves and transported into growth cones. Conclusions. Our results suggest that measuring the length of motor axon outgrowth by ChAT immunostaining is reliable. ChAT staining provides a more convenient method for evaluating the rate of motor axon outgrowth in a mixed nerve.