AIP
- AH receptor-interacting protein
- AIP Records
- Action International Pictures
- Acute intermittent porphyria
- Acute interstitial pneumonitis
- Adaptive Internet Protocol
- Aeronautical Information Publication
- Afghan Islamic Press
- Agreement in principle
- Air-independent propulsion
- Airport Improvement Program
- Alaskan Independence Party
- Aluminium phosphide
- American Independent Party
- American Industrial Partners
- American Institute of Parliamentarians
- American Institute of Philanthropy
- American Institute of Physics
- American International Pictures
- Arrow information paradox
- Art Institute of Pittsburgh
- Artistic Infusion Program
- Astrophysical Institute Potsdam
- Australian Institute of Physics
- Autoimmune pancreatitis
- Azərbaycan İslam Partiyası
- Open Archival Information System
- Secondary air injection