Agricultural Technical Institute, a campus located in Wooster, Ohio part of The Ohio State University system.

A. T. I., a 1944 collection of poems by A. P. Herbert

Ati (queen), Queen of Punt ca. 1490 BCE.

ATI Technologies Inc., a subsidiary of AMD that manufactures graphics cards.

Accurate Technologies Inc., a manufacturer of software and hardware tools for vehicle Engine Control Unit development

Allied Telesis Inc., a manufacturer of computer network products, formerly known as Allied Telesyn.

The three-letter acronym ATI may stand for:

Allegheny Technologies Inc., a steel company that trades on the New York Stock Exchange under the symbol 'ATI'.

Air Transport International, a worldwide charter cargo airline.

Advanced Training Institute, a home education program developed by Institute in Basic Life Principles.

Tunisian Internet Agency (Agence tunisienne d'Internet), a Tunisian ISP

Ati, Chad, a town in Chad.

Ati (tribe), the earliest inhabitants of the Visayas in the Philippines

Ati-Atihan Festival, an annual celebration held in the province of Aklan in the Philippines.

Auckland Technical Institute, now Auckland University of Technology

Atlantic Turbines Incorporated, a Pratt and Whitney certified aircraft engine overhaul company based in Summerside, PEI