We use the Kubo formalism to calculate the transresistivity ρ21 for carriers in coupled quantum wells in a large perpendicular magnetic field B. We find that ρ21 is enhanced by approximately 50–100 times over that of the B=0 case in the interplateau regions of the integer quantum Hall effect. The presence of both electron-electron interactions and Landau quantization results in (i) a twin-peaked structure of ρ21(B) in the interplateau regions at low temperatures and (ii) for the chemical potential at the center of a Landau level band, a peaked temperature dependence of ρ21(T)/T2.