The blue nuthatch (Sitta azurea) is a species of bird in the family Sittidae. It is a medium-sized nuthatch, measuring 13.5 cm (5.3 in) in length. The species, which lacks sexual dimorphism, has dramatic coloration unlike any other member of its genus. Its head is black or blackish-blue dark blue upper parts close to purple with azure feathers. The wings are edged with black. The throat and chest are white or a washed buff color, contrasting with the upper and the belly of a very dark blue; the feathers are generally clear, blue-gray or purplish.