The 21st Louisiana Infantry Regiment, also called the McCown Regiment, was an infantry regiment from Louisiana that served in the Confederate States Army during the American Civil War. Six of its companies formed the 5th Louisiana Infantry Battalion organized in September 1861, which fought in the Battle of Belmont as cannoneers. The battalion was brought up to regimental strength, becoming the 21st Louisiana, by the addition of four companies in February 1862. After service at Island Number Ten, Fort Pillow, and the Siege of Corinth, the regiment was disbanded due to its high desertion rate.