Glucose-inhibited division protein A (GidA) acts in tRNA modification. It has been suggested that GidA is involved in the biosynthesis of the hypermodified nucleotide 5-methylaminomethyl-2-thiouridine in the wobble position of bacterial tRNAs, which stabilizes codon-anticodon interactions. Thermus thermophilus HB8 has a putative small gidA gene in addition to the normal gidA gene. The crystallization and preliminary X-ray crystallographic studies of the product of this small gidA gene (GidA(small)) are reported here. The crystals belong to space group P3(1)21 or P3(2)21, with unit-cell parameters a = b = 78.51, c = 66.10 A and one monomer per asymmetric unit. The crystals were found to diffract X-rays to beyond 1.65 A resolution.