||The state of the art in prosthetic arm/hand technology has not changed much since the 1950s. The desire to bring more intuitive and less cumbersome control of prosthetic arms/hands has caused neuroprosthetics researchers to investigate the use of myoelectric and neural signal recording devices to gain access to biological signals for the purpose of controlling a prosthetic limb. We hypothesized that the use of Implantable MyoElectric Sensors (IMES), wireless electromyogram (EMG) signal sensors, would allow safe and effective access to signals sufficient to control a dexterous prosthetic hand while avoiding the risks and disadvantages of surface and wired implantable EMG sensors. Therefore, we trained a macaque monkey to perform cued flexions, extensions, and combined flexions of the thumb, index finger, and middle finger using a manipulandum that used microswitches to monitor subtle, low-force finger flexions and extensions. We evaluated the ability to decode the monkey's finger flexion intent based on the recorded EMG that occurred during the behavioral finger movement task with two different algorithms. We concluded that the IMES can provide stable, independent access to EMG from extrinsic finger muscles that could be used to successfully control a dexterous prosthetic hand.