Replication technologies such as embossing, molding and casting are highly attractive for the fabrication of surface relief hologram and diffractive optical element (DOE) microstructures. They have very high resolution, typically in the nanometer range, and allow the fabrication of a large area, complex microstructure by low cost, high volume industrial production processes. Their use is already well established for gratings, white light holograms, and diffractive foil with typical relief structure shallower than 1 μm and the extension to the fabrication of deeper and higher aspect ratio microstructure is underway. The combination of replication technology with other processes such as dry etching and thin film coating can also offer new possibilities in the design of DOEs suitable for mass production. Replication is expected to become a key technology for the microfabrication of a wide range of DOEs in the future. We review the major hologram and DOE replication techniques and describe recent work and results.