This work presents a wireless 401-406 MHz on-off keying (OOK) transceiver (TRX) analogue front-end for medical implantable communication systems (MICS). The transmitter (TX) part consists of a voltage-controlled oscillator (VCO), a fractional-N phase-locked loop (PLL) and an output buffer for OOK modulation. The receiver (RX) front-end implemented based on a low intermediate-frequency (IF) homodyne RX architecture comprises a balun low-noise amplifier (LNA), a Gilbert mixer and a variable gain amplifier (VGA). The RX re-uses the signal generated by the TX as its local oscillation (LO) signal. A proof-of-concept circuit prototype has been fabricated in a 180-nm BiCMOS technology. Experimental results show the PLL frequency can be adjusted over the entire MICS band with a frequency resolution of 0.33 MHz. Its phase noise is-100 dBc/Hz at 1-MHz offset frequency. Additionally, the TX exhibits a maximal output power of 4.6 dBm. The complete RX front-end achieves a noise figure below 8.4 dB and a high conversion gain of 75 dB. The TX and RX consume a DC power of 23 mW and 27.5 mW, respectively. The data rate of the whole TRX reaches 1 Mbit/s which is the highest among the state-of-the-art MICS TRXs.