Cryptosporidium parvum is one of the major causes of waterborne diseases worldwide. This protozoan parasite depends mainly on the anaerobic oxidation of glucose for energy production. In order to identify the differences in the three-dimensional structure of key glycolytic enzymes of C. parvum and its human host, we have expressed, purified and crystallized recombinant versions of three important glycolytic enzymes of the parasite, namely, glyceraldehyde 3-phosphate dehydrogenase, pyruvate kinase and lactate dehydrogenase. Lactate dehydrogenase has been crystallized in the absence and in the presence of its substrates and cofactors, while pyruvate kinase and glyceraldehyde 3-phosphate dehydrogenase were crystallized only in the apo-form. X-ray diffraction data have been collected for all crystals. © 2005 Elsevier B.V. All rights reserved.