Pantothenate kinase is an essential enzyme in the bacterial life cycle. It catalyzes the phosphorylation of pantothenate (vitamin B5) to 4'-phosphopantothenate, the first step in the coenzyme A biosynthetic pathway. The enzyme from Mycobacterium tuberculosis, MW 35.7 kDa, has been cloned, expressed, purified and crystallized in two different trigonal crystal forms, both belonging to space group P3(1)21. Two complete data sets of resolution 2.5 A (form I) and 2.9 A (form II) from crystals with unit-cell parameters a = b = 78.3, c = 115.45 A and a = b = 107.63, c = 89.85 A, respectively, were collected at room temperature on a home X-ray source. Structures of both crystal forms were solved for one subunit in the asymmetric unit by molecular replacement.