McIntosh and Fildes' anaerobic jar is an instrument used in the production of an anaerobic environment.

This method of anaerobiosis as others is used to culture bacteria which die or fail to grow in presence of oxygen (anaerobes).

[1][2] It was originally introduced by James McIntosh, Paul Fildes and William Bulloch in 1916.

[3] McIntosh and Fildes, after whom the device has been named, published an improved version in 1921.

[4] The jar, about 20 by 12.5 inches (510 mm × 320 mm) is made of metal.