The 31st Battalion, Royal Queensland Regiment (31 RQR) was a Reserve infantry battalion of the Australian Army. Although it was officially formed as 31 RQR in 1965 the battalion can trace its lineage back to units formed in 1881 as part of the colonial defence forces of the state of Queensland. In January 2008 the battalion was amalgamated with the 42nd Battalion, Royal Queensland Regiment (42 RQR) to form the 31st/42nd Battalion, Royal Queensland Regiment (31/42 RQR).