The 3rd Chemical Brigade is a training brigade of the United States Army based at Fort Leonard Wood, Missouri, retaining for historic reasons its name.

The unit was reorganized and redesignated as the 3rd Chemical Mortar Battalion on 11 March 1945.

The unit reactivated at Fort Bragg, North Carolina on 18 September 1950, but again inactivated there on 5 February 1953.

The unit reconstituted on 1 October 1999 in the Regular Army and was redesignated as 3rd Chemical Brigade.

[3] This article incorporates public domain material from 3d Chemical Brigade Lineage and Honors.