The Otago Infantry Regiment (Otago Regiment) was a military unit that served within the New Zealand Expeditionary Force (NZEF) in World War I during the Gallipoli Campaign (1915) and on the Western Front (1916–1919). This Regiment and the Otago Mounted Rifles Regiment were composed mostly of men from Otago and Southland. The Otago Infantry Regiment represented the continuation of the Dunedin and Invercargill Militia Battalions formed in 1860.