A series of dimethylsiloxane linked cyanate ester monomers (NCOC6H4(CH2)3(Si(CH3)2O)nSi(CH2)3C6H4OCN, n = 1, 2, 3) have been synthesized and characterized. Monomer melting points range from 5 to −12 °C, and characterization includes 1H, 13C NMR, and IR spectroscopies and DSC. Thermoset formation occurs by a cyclotrimerization of the cyanate group to a cyanurate structure. Cured resins are homogeneous rubbery castings with Tg ranging from 15 to −43 °C. Dielectric constants display little dependence on siloxane chain length but a strong dependence on frequency (2.5/15 GHz; 2.85/1 GHz). The corresponding loss tangent increases with siloxane chain length and displays a small frequency dependence.