ATSI

ATSI may refer to:


 * Atsi, another name for the Zaiwa language of China and Burma
 * Aboriginal and Torres Strait Islander people, the first peoples of Australia. The ATSI abbreviation is often considered disrespectful.
 * Ahtna Technical Services Incorporated a subsidiary of Ahtna, Incorporated
 * NLR Air Transport Safety Institute
 * Anatomy Trains Structural Integration, a school related to Rolfing