Objective The aim of this study was to observe the growth difference and expression of cytochrome C of skin hair follicles in neonatal mice .Methods The morphology of different skin hair follicles of neonatal mice ( postnatal day 1-9)were observed by HE staining histology and cytochrome C was detected by immunohistochemistry .Results The skin hair follicles in different parts of neonatal mice showed differences not only in morphology but also in developmental pe -riods.Hair follicle growth in the back and tail skin had a nonlinear and growing period .After the nonlinear and growing pe-riod they began to grow rapidly .The tail development was slightly slower than that on the back .The hair follicles of vibris-sae were very special , and started to develop without a stable period .Conclusions The results of morphological observa-tion and cytochrome C immunohistochemistry demonstrate that differences exist in the hair follicle morphology and develop -mental times in the skin of different parts of the body in neonatal mice .