By combining laser interference lithography and metal-assisted etching we were able to produce arrays of silicon nanowires with uniform diameters as small as 65 nm and densities exceeding 2 x 10(7) mm(-2). The wires are single crystalline, vertically aligned, arranged in a square pattern and obey strict periodicity over several cm(2). The applied technique allows for a tailoring of nanowire size and density. Using a controlled and scalable process to fabricate sub-100 nm silicon nanowires is an important step towards the realization of cost-effective electronic and thermoelectric devices.