Pathogen-inducible oxygenase (PIOX) is a heme-containing membraneassociated protein found in monocotyledon and dicotyledon plants that utilizes molecular oxygen to convert polyunsaturated fatty acids into their corresponding 2R-hydroperoxides. PIOX is a member of a larger family of fatty-acid -dioxygenases that includes the mammalian cyclooxygenase enzymes cyclooxygenase 1 and 2 (COX-1 and COX-2). Single crystals of PIOX from rice (Oryza sativa) have been grown from MPD using recombinant protein expressed in Escherichia coli and subsequently extracted utilizing decyl maltoside as the solubilizing detergent. Crystals diffract to 3.0 Å resolution using a rotatinganode generator and R-AXIS IV detector, and belong to space group P1. Based on the Matthews coefficient and self-rotation function analyses, there are presumed to be four molecules in the asymmetric unit related by noncrystallographic 222 symmetry.