3rd Regiment, Canadian Mounted Rifles

The 3rd Regiment, Canadian Mounted Rifles, CEF, was a mounted infantry unit of the Canadian Expeditionary Force in the First World War. It was formed in November, 1914, at Medicine Hat and recruited personnel in Alberta. It sailed to England in June, 1915, and after training arrived in France on September 22, 1915. It served in the field as dismounted infantry until December, 1915.

On January 1, 1916, the six regiments of Canadian Mounted Rifles were converted to infantry and reorganized into the four battalions of the 8th Canadian Infantry Brigade. The personnel of the 3rd Regiment were absorbed into the 1st and 2nd Battalions, CMR.

The 3rd Regiment is perpetuated by the South Alberta Light Horse.