Regions of light-emitting porous silicon fabricated by anodic electrochemical etching have been patterned by photolithography. Samples were spin-coated with photoresist, and contact photolithography was used to define the desired mask pattern. Exposure of unmasked sample regions to an isotropic oxygen plasma in a barrel reactor results in a dramatic reduction of the visible photoluminescence. The resulting patterns exhibit high contrast, with a minimum feature size of 4 mum. The patterns are remarkably stable, withstanding both chemical treatment and atmospheric contamination.