Two distinct azurins named azurin-I and azurin-II were isolated from Alcaligenes xylosoxidans GIFU 1051 (AzG-I and AzG-II). They have been purified and crystallized. The crystals of AzG-I belong to the monoclinic crystal system, space group C2, unit-cell parameters a = 130.6, b = 54.4, c = 74.7 Å, β = 96.1°. The crystals of AzG-II belong to the tetragonal crystal system, space group P4122 or P4322, unit-cell parameters a = b = 52.6, c = 100.7 Å. Both crystals diffract up to 2.0 Å resolution and are suitable for X-ray crystallographic studies.