NikA, a periplasmic nickel-binding protein involved in nickel-repellent chemotaxis has been crystallized. The crystals are hexagonal with space group P6(2) (or its enantiomorph) with a = 160.3 Angstrom and c = 138.4 Angstrom and they diffract to at least 3.0 Angstrom resolution in the laboratory NikA presents sequence homology with several periplasmic solute-binding proteins from Gram-negative bacteria.