The Chromatiaceae-specific glutathione amide reductase (GAR) belongs to the well known family of the glutathione reductases, even though differences in both substrate (glutathione amide instead of glutathione) and coenzyme (NADH instead of NADPH) specificities are reported. Crystals of the GAR enzyme from Chromatium gracile have been grown at 294 K by the hanging-drop vapour-diffusion method using lithium sulfate as a precipitant in the presence of nickel ions. The crystals belong to space group P4(1), with unit-cell parameters a = b = 71.93, c = 223.85 A, alpha = beta = gamma = 90 degrees and one dimer per asymmetric unit. A full set of X-ray diffraction data was collected to 2.1 A resolution with a completeness of 95.2%. Structure determination via the method of molecular replacement is under way.