The ultrastructure of muscle dedifferentiarion and redifferentiation was observed during hind limb regeneration in a larval stage (number 53) of Bufo regularis. It was found that the young, forming muscle fibres with low level of differentiation, can easily loose its morphological characteristic features and dedifferentiate into blastemal cells from which new muscle fibres redifferentiate. Dedifferentiated cells were acquiring characteristics of actively growing cells reflecting their transformation into blastemal mesenchyme cells and then into redifferentiated muscle fibres. Satellite cells were not observed in the formation of the new myotubes. The absence of satellite cells in muscle fibres, in the present study, was suggested to be due to the low level of differentiation of muscle fibres, since the observed cells were either myogenic cells or early differentiating muscle fibres with incomplete myofibril set. Cells must be confined to the well differentiated mature muscles. Macrophages were suggested to induce young muscle fibres differentiation via releasing soluble factors during removal of cellular debris.