Controlling a machine based on the myoelectric signal is very natural and is described as controlling the phantom hand for transradial amputee people using a powered prosthetic hand. This chapter introduces the technology associated with the recording and analysis of myoelectric signals, and describes the implementation of myoelectric-based human–computer interface (HCI). It then describes the limitations and challenges that exist due to the gross nature of the signal and presence of multiple muscle activities in the recordings. Finally, the current research activities that are identifying specific hand and finger movements and future directions in this field are described.