A low-cost process for replicating diffractive optics has been demonstrated using radiation-curable liquid photopolymers on plastic substrates. Two- and eight-level f/10 quartz master elements were embossed into liquid photopolymers and subsequently cured under pressure using high-intensity ultraviolet (UV) radiation. The quartz master is easily separated from the hardened replica and immediately available for reuse. High-fidelity replicas with the same surface polarity as the original master can be made from nickel electroforms. For obtaining good optical image quality replicas, quartz masters were found to be significantly better than nickel masters. High- fidelity replication of surface relief structures was verified using an optical microscope, a Scanning Electron Microscope (SEM), and a 2-D scanning profilometer. Nearly theoretical diffraction efficiency (39.4% versus 40.5%) was achieved with the two-level f/10 replica. Optical image quality was degraded by substrate warping and submicron surface roughness as evidenced by increasing distortion of the blur spot over larger replica diameters. Less than 10% shrinkage was measured in the vertical dimension with no shrinkage measured in the horizontal plane. Although optical image quality applications are limited, the process is suitable for applications such as polarizers and microlens arrays.