Malate dehydrogenase (MDH) is an enzyme of the citric acid cycle that catalyzes the reversible oxidation of malate to oxaloacetate with the concomitant reduction of NADH. The 2.17 Å resolution crystal structure of the malate dehydrogenase from Vibrio vulnificus CMCP6 was determined by molecular replacement using the structure of the malate dehydrogenase from Escherichia coli (PDB code 3HHP) as a model. The asymmetric unit has four molecules that form two dimmers with the total buried surface area of 3,570 Å2. The protein exhibits an α/β fold with the presence of the Rossman fold sitting at the dimerization interface. The active site loop (residues 81 through 86) in all four subunits is disordered.