| 1 | MDP | Medallion Air | Founded in 2009. Merged into Ten Airways in July 2013. | RO | AVCODES |
| 2 | MDP | Mexican Pacific R.R. Co., Inc. (transferred to Ferrocarriles Nacionales de Mexico) | eliminated 10/1988 | | NAKINA |
| 3 | MDP | Mexican Pacific R.R. Co., Inc. (Ferrocarril Mexicano del Pacifico, S.A.) | 1/1975-1/1980 | | NAKINA |
| 4 | MDP | Mexican Pacific R.R. Co., Inc. (Ferrocarril Mexicano del Pacifico, S.A.) | 1/75-1/80 | | NRHS |
| 5 | MDP | Mexican Pacific R.R. Co., Inc. (transferred to Ferrocarriles Nacionales de Mexico) | eliminated 10/88 | | NRHS |
| 6 | MDP | MEXICAN PACIFIC RAILROAD (FERROCARRIL MEXICANO DEL PACIFICO, SA) | | | PWRC |
| 7 | MDP | Mexican Pacific Railroad (Ferrocarril Mexicano del Pacifico) | | | RSRV |
| 8 | MDPB | MODERN DISPOSAL SERVICES INC | | | SCAC4 |
| 9 | MDPD | MICELI DAIRY PRODUCTS INC | | | SCAC4 |
| 10 | MDPE | MED PACIFIC EXPRESS | | | SCAC1 |
| 11 | MDPE | MARTINEZ DE LA PENA, JULIO CESAR | | | SCAC4 |
| 12 | MDPF | MID-AMERICA CARRIER GROUP CORPORATI | | | SCAC4 |
| 13 | MDPI | McCARTHY, DAVID P | | | SCAC1 |
| 14 | MDPJ | METAMORFOSIS DOCUMENTATION PROJECT | | | SCAC4 |
| 15 | MDPK | MID-PLAINS IMPLEMENTS LTD | | | SCAC4 |
| 16 | MDPL | MADERA PALLETS&TRANSPORTS | | | SCAC1 |
| 17 | MDPL | MADERA PALLETS & TRANSPORT | | | SCAC4 |
| 18 | MDPM | MID-ATLANTIC PETROLEUM TRANSPORT LL | | | SCAC4 |
| 19 | MDPN | MINNESOTA DEPARTME | | | SCAC4 |
| 20 | MDPO | MEDINA TRANSPORT, INC. | | | SCAC1 |
| 21 | MDPO | MCDONOUGH PROJECT SERVICES LP | | | SCAC4 |
| 22 | MDPO | Městský dopravni podnik Opava | City: Opava | CZ | TRAFFIC |
| 23 | MDPP | MDP TRANSPORTATION | | | SCAC4 |
| 24 | MDPR | M & D PROPERTIES LTD | | | SCAC4 |
| 25 | MDPT | MID-PACIFIC TRANSPORTATION INC | | | SCAC4 |
| 26 | MDPU | MODERN SHIPPING LINES CO LTD | | HK | BIC |
| 27 | MDPV | MIDWEST ASPHALT CORP | | | SCAC4 |
| 28 | MDPY | MODIPO AUTO LLC | | | SCAC4 |
