| Abbreviation | Definition |
|---|---|
| AATA | Amarillo Area Tennis Association |
| AATS | Annapolis Area Tennis School |
| AAYT | Arthur Ashe Youth Tennis |
| ABTL | Ace Bandage Tennis League |
| ACTT | Avila Charity Tennis Tournament |
| AFTS | Association Française de Tennis des Seniors |
| AILTA | All India Lawn Tennis Association |
| AITA | All India Tennis Association |
| AJTF | Alamance Junior Tennis Foundation |
| ALTA | Atlanta Lawn Tennis Association |
| ALTB | Arnhemsche Lawn Tennis Bond |
| ALTB | Aruba Lawn Tennis Bond |
| AMTA | Anderson Mill Tennis Association |
| APTA | American Platform Tennis Association |
| APTTA | Andhra Pradesh Table Tennis Association |
| ATA | American Tennis Association |
| ATA | Arizona Tennis Association |
| ATF | Asian Tennis Federation |
| ATP | American Tennis Promotion |
| ATP | Anonymous Tennis Players |