The 90th Light Anti-Aircraft Regiment, Royal Artillery, (90th LAA Rgt) was an air defence unit of the British Army during World War II. Initially raised as an infantry battalion of the South Wales Borderers in 1940, it transferred to the Royal Artillery in 1941. It served with 1st Infantry Division in the final stages of the Tunisian Campaign, distinguished itself in the Anzio landings and subsequent fighting, and continued serving in Italy before being disbanded at the beginning of 1945.