The paper presents the proposed wireless brain signal acquisition circuits f or body sensor network. Considering the power-efficient communication in the body sensor network, the required low-power analog integrated circuits (ICs) are developed for a wireless brain signal acquisition system. To acquire the electroencephalogram (EEG) signal, this paper proposes an analog front-end (AFE) circuit, including only one low-noise amplifier with chopping techniques and one high-pass sigma-delta modulator (HPSDM), which can be applied as a sensing circuit for EEG signal acquisition systems. To transmit the EEG signal through wireless communication, a quadrature CMOS voltage-controlled oscillator and a 2.4 GHz direct-conversion transmitter with a power amplifier and up-conversion mixer are al so developed. In the receiver, a 2.4 GHz fully integrated CMOS radio-frequency front-end is also implemented. The circuits have been implemented to fit the specifications of the IEEE 802.15.4 2.4 GHz standard. The low-power ICs of the wireless EEG acquisition systems have been fabricated using a 0.18 μm TSMC CMOS standard process. The measured results reveal that the proposed low-power analog front-end ICs can be used for the wireless brain signal acquisition.