Materials with aligned porous structures have broad potential in applications such as organic electronics, microfluidics, and tissue engineering. Materials of this type can be fabricated using techniques such as microfabrication, soft lithography, and photolithography. Directional freezing is a cheap, simple, and novel route to prepare aligned porous materials in the form of 2D surface patterns or 3D monolithic structures. A solvent - typically water but also organic solvents or carbon dioxide - is frozen unidirectionally and the pore structure is templated from the aligned solvent crystals that are formed. These methods can produce complex composite materials with a range of aligned pore architectures.