The aliphatic amidase (acylamide amidohydrolase; EC 3.5.1.4) from Pseudomonas aeruginosa is a hexameric enzyme composed of six identical subunits with a molecular weight of approximately 38 kDa. Since microbial amidases are very important enzymes in industrial biocatalysis, the structural characterization of this enzyme will help in the design of novel catalytic activities of commercial interest. The present study reports the successful crystallization of the wild-type amidase from P. aeruginosa. Native crystals were obtained and a complete data set was collected at 1.4 A resolution, although the crystals showed diffraction to 1.25 A resolution. The crystals were found to belong to space group P6(3)22, with unit-cell parameters a = b = 102.60, c = 151.71 A, and contain one molecule in the asymmetric unit.