Dielectric constants of allyl methacrylate-methyl methacrylate copolymers are measured in toluene solution at a constant frequency of 2 MHz, within a wide temperature range (20-70 degrees C). Soluble copolymers have been prepared by group transfer copolymerization. Dipole moments are calculated from Guggenheim-Smith equation. The effects of allyl group on the dipole moments of copolymers in a slightly polar medium are discussed.