We report on transport measurements in a novel system composed of two parallel 2D electron and hole gases separated by a barrier which is high enough to prevent tunneling and recombination while thin enough to allow for strong interlayer Coulomb interaction. Separate electrical contacts to each layer and independent control of both carrier densities facilitate a detailed study of the electron-hole interaction. Current driven in one layer is found to induce opposite current in the other layer. The measured electron-hole momentum-transfer rate is a factor of 5 to an order of magnitude larger than in previous experiments on electron-electron scattering and calculations based on Coulomb scattering theory. © 1992 The American Physical Society.