A new interconnect solution with plastic waveguide is demonstrated. The system consists of a pair of transceivers and a plastic waveguide. Millimeter wave signal is transmitted in a low-cost long piece of solid plastic dielectric acting as a waveguide. The plastic waveguide medium offers a large bandwidth for data communication using mm-wave carrier frequencies. Plastic waveguide interconnects do not require costly electrical-to-optical and optical-to-electrical conversion devices or precise alignment and offer longer transmission distances than wireless solutions due to better field confinement and lower path loss. Multiple plastic waveguides can be used in parallel and the modulated data at different frequencies can be multiplexed to increase the data rate. The demonstrated transceiver chips operate at carrier frequencies of 57 GHz and 80 GHz, and are fabricated in 40 nm low-power logic CMOS. The total area and power consumption of two transceivers are 0.41 mm2 and 140 mW, respectively. The fabricated demonstrator with Yagi-couplers achieves full-duplex transmission of 12.5 Gb/s ASK modulated signal in each direction over the 120 mm polystyrene waveguide with no equalization. The observed bit error rates for both channels are less than 1e-12 for a PRBS length of 2^7-￼ 1 at the total data rate of 25 Gb/s. This paper shows the feasibility of the plastic waveguide interconnect as a promising alternative to electrical, optical, and wireless interconnects.