DNA gyrase subunit B C-terminal domain (GyrB-CTD) is a functional module of DNA gyrase which participates in forming the core of DNA gyrase and plays critical roles in G-segment binding and T-segment loading and passage. Here, the purification, crystallization and preliminary X-ray crystallographic studies of GyrB-CTD from Mycobacterium tuberculosis H37Rv are reported. Diffraction data were collected from crystals of native GyrB-CTD and its selenomethionine derivative to resolutions of 2.8 and 3.0 A, respectively. These crystals belonged to space group P2(1)2(1)2(1) with similar unit-cell parameters. The native protein crystals had unit-cell parameters a = 52.831, b = 52.763, c = 192.579 A.