Hyperbaric oxygen (HBO) treatment was shown to be beneficial as an additional treatment for ischemic muscles in crush injuries and ischemia-reperfusion injuries. The purpose of this study was to assess the influence of hyperbaric oxygen treatment on transcriptional myogenic factors during muscle regeneration. Those factors (MyoD, myf5, myogenin, mrf4) are essential for determination and differentiation of skeletal muscle tissue and together with several other factors control gene expression during myogenesis. The process of regeneration in rat masseter muscle was provoked with injection of local anesthetic bupivacaine hydrochloride. Following injection, the animals were treated once daily in hyperbaric chamber from one to ten days and than sacrificed. Immunohistochemical and Western blot analysis of frozen masseter muscle samples showed a transient upregulation of myoD and myogenin transcriptional factors in the muscles of hyperbaric oxygen treated rats and of rats that have not been treated after the injury. HBO treatment had no effect on the expression of MyoD and myogenin transcriptional factors in the regenerating rat masseter muscle.