- Access
- Accredited Standards Committee (ASC)
- Administrative Code Sets (ACS)
- Administrative Requirements
- Administrative Simplification (A/S)
- Administrative safeguards
- Admission Date
- Affliated Covered Entity
- American Association for Homecare (AAHomecare)
- American Dental Association (ADA)
- American Health Information Management Association (AHIMA)
- American Hospital Association (AHA)
- American Medical Association
- American Medical Informatics Association
- American National Standards (ANS)
- American National Standards Institute
- American Public Human Services Association (APHSA)
- American Society for Testing and Materials (ASTM)
- Ancillary Services
- Association for Electronic Health Care Transactions (AFEHCT)
- Authentication
- Authorization
- Automated Clearinghouse (ACH)
- Availability