This paper presents an overview of multimode waveguides and waveguide components formed from siloxane polymer materials which are suitable for use in optical interconnection applications. The components can be cost-effectively integrated onto conventional PCBs and offer increased functionality in optical transmission. The multimode waveguides exhibit low loss (0.04 dB/cm at 850 nm) and low crosstalk (> -30 dB) performance, large alignment tolerances and negligible mode mixing for short waveguide lengths. Error-free data transmission at 10 Gb/s over 1.4 m long waveguides has been successfully demonstrated. Waveguide crossings exhibit very low excess losses, below 0.01 dB/crossing, and excellent crosstalk performance. Low loss is obtained for waveguide bends with radii of curvature larger than 8 mm and 6 mm for 90deg; and S-shaped bends respectively. High-uniformity splitting is achieved with multimode Y-splitters even in the presence of input misalignments. Y-combiners are shown to benefit from the multimode nature of the waveguides allowing low loss combining (4 dB for an 8×1 device). A large range of power splitting ratios between 30% and 75% is achieved with multimode coupler devices. Examples of system applications benefiting from the use of these components are briefly presented including a terabit capacity optical backplane, a radio-over-fibre multicasting system and a SCM passive optical network.