This paper presents a 0.9 g battery-free wireless stimulator for neural repair and regeneration. The stimulator can deliver fully programmable charge-balanced current-mode stimulation. Wireless power transfer is used to eliminate batteries to reduce device size and weight for small animals like mice. Infrared communication is integrated to wirelessly control the device and update the stimulation parameters. The whole design uses only low-cost off-the-shelf components and yet consumes only 0.81 mA current while delivering 0.2 mA stimulation at 285.7 Hz. The prototype was validated in vivo and successfully activated endogenous neural precursor cells with effectiveness comparable to a wired stationary instrument.