The regenerative power of Ephippiger ephippiger (Tettigoniidae) after the experimental removal at hatching of both tibia and tarsi of the foreleg was investigated. The lost leg parts were successively regenerated with increasing degrees of morphological differentiation. This process has an effect on the postembryonic development because, subsequently, the first larval stage is prolonged. In adults, the regenerated limb is one-quarter of the length of normal tibia and tarsi together, but it often has the gross morphology of a normal leg. The pattern of innervation and the distribution of receptor is completely changed, and the complex tibia1 organ is not reformed. The tympanic nerve is missing, and the axons of the regenerated receptor cells form new nerves that join the leg nerve.Physiological recordings of acoustic-vibratory, ventral nerve cord neurons revealed the possibility of excitatory input from the contralateral, intact acoustic receptors. However, the magnitude of the response is not fully restored. Behavioral experiments showed that the operated animals are not able to compensate for the unilateral deprivation of sensory input and fail in localization of the conspecific song.