A compact folded planar inverted F antenna (PIFA) for ultra wideband (UWB) on-body communications is proposed. A tapered shape is employed into the radiating plate of the proposed antenna for wideband impedance matching. For size miniaturization, both the radiating plate and the grounding plate are folded. The folded radiating plate is designed to correspond to and be close to the folded grounding plate to create a capacitive load and to lower the resonant frequency for further size miniaturization. Due to the compact thickness of the proposed antenna, it can be easily attached to the human body with comfort. The grounding plate, the grounding plate is used as a reflector to steer radiation along the surface of human body as well as enhance the transmission efficiency of on-body communications. The proposed antenna covers the bandwidth from 6 to 10 GHz with 5∼7 dBi radiation gain, which is suitable for on-body communications.