The crystal structure of the tetrameric form of D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH) isolated from rabbit muscle was solved at 2.4 A resolution after careful dynamic light-scattering experiments to find a suitable buffer for crystallization trials. The refined model has a crystallographic R factor of 20.3%. Here, the first detailed model of a mammalian GAPDH is presented. The cofactor NAD(+) (nicotinamide adenine dinucleotide) is bound to two subunits of the tetrameric enzyme, which is consistent with the negative cooperativity of NAD(+) binding to this enzyme. The structure of rabbit-muscle GAPDH is of interest because it shares 91% sequence identity with the human enzyme; human GAPDH is a potential target for the development of anti-apoptotic drugs. In addition, differences in the cofactor-binding pocket compared with the homology-model structure of GAPDH from the malaria parasite Plasmodium falciparum could be exploited in order to develop novel selective and potential antimalaria drugs.