A thymidylate kinase catalyzes the reversible phosphoryl transfer from adenosine triphosphate (ATP) to thymidine monophosphate (dTMP) to form thymidine diphosphate (dTDP). This enzyme from Vibrio cholerae O1 biovar eltor str. N16961 was co-crystallized with thymidine. Crystal diffracted to 2.25 Å resolution and a molecular replacement solution was obtained using the structure of the Vibrio cholerae O1 biovar eltor str. N16961 thymidylate kinase (PDB ID 3LV8).