A flexible diversity antenna using zeroth-order resonance (ZOR) for WBAN applications is proposed to improve performance and overcome multipath fading. The dimension of the proposed diversity antenna, including the system ground, two antenna elements, and the decoupling network is 44mm × 35mm × 0.127mm. When the antenna is located on a semi-solid flat phantom with equivalent electrical properties of a human body, the S₁₁ and S₂₂ values of the proposed antenna at 2.45GHz are -22.8dB and -25.4dB, respectively. The measured specific absorption ratio (SAR) values of the antenna elements #1 and #2 are 0.54W/kg and 0.75W/kg (1g tissue) and mean powers delivered from the two ports are almost identical since the proposed antenna has a measured ECC of 0.021MEG ratio of 0.33dB at 2.45GHz.