Micro- and nanoporous membranes have a wide range of applications in many fields, including medical diagnostics, drug delivery, and hemodialysis. Ultrananocrystalline diamond coatings are becoming more and more significant in medical applications because of the highest degree of biocompatibility, unmatched by other materials. The pores ranging in diameter from 100 to 2000 nm have been fabricated in a 1-mu m-thick ultrananocrystalline diamond film on silicon wafers using e-beam and optical lithography, reactive ion etching, and laser writing. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3501345]