| 1 | MF | Xiamen Airlines | ICAO: CXA, Callsign: Xiamen Air, IATA Prefix: 731, IATA designator changed to MF | PRC | AVCODES |
| 2 | MF | Zimex Aviation Limited | ICAO: IMX, Callsign: Zimex, IATA designator changed to C4* | CH | AVCODES |
| 3 | MF | Marshall's Flying Services Ltd. | Callsign: Marshall, | GB | AVCODES |
| 4 | MF | MAM Aviation Ltd. | ICAO: MMM, Callsign: Mamair, Name changed to Marine and Aviation Management International | GB | AVCODES |
| 5 | MF | Marine and Aviation Management International | ICAO: MMM, Callsign: Mamair, Name changed from MAM Aviation Ltd. | GB | AVCODES |
| 6 | MF | Xiamen Airlines | ICAO: CXA, Callsign: Xiamen Air, IATA Prefix: 731, IATA designator changed from MF* | PRC | AVCODES |
| 7 | MF | My Freighter Airlines | ICAO: MFX, Callsign: Whitebird, IATA Designator changed to C6. | UZ | AVCODES |
| 8 | MF | Middle Fork | 1/1975-1/1980 | | NAKINA |
| 9 | MF | Middle Fork | 1/75-1/80 | | NRHS |
| 10 | MF | MIDLAND FORK RAILROAD | | | PWRC |
| 11 | MF | Middle Fork Railroad | | | RSRV |
| 12 | MFA | Martyn Fiddler Associates | Callsign: Seahorse, | GB | AVCODES |
| 13 | MFA | Martyn Fiddler Associates | | | ICAO1 |
| 14 | MFAA | MFA INCORPORATED | | | SCAC4 |
| 15 | MFAB | METALFAB LTD | | | SCAC4 |
| 16 | MFAC | MASTER FREIGHT AMERICA CORP | | | SCAC4 |
| 17 | MFAD | MOVEFREIGHT | | | SCAC4 |
| 18 | MFAE | MALFATONE, RALPH & SON INC | | | SCAC4 |
| 19 | MFAF | MATHESON FAST FREIGHT, INC | | | SCAC1 |
| 20 | MFAG | Müller Gleisbau AG | | CH | VKM |
| 21 | MFAH | MORGAN FUEL AND HEATING CO INC | | | SCAC4 |
| 22 | MFAN | MASTRE, FRANK | | | SCAC4 |
| 23 | MFAO | MISTY FJORDS AIR & OUTFITTING | | | SCAC4 |
| 24 | MFAP | MFS SYSTEMS TWO ZERO ZERO SEVEN (20 | | | SCAC4 |
| 25 | MFAQ | MANUFACTUROS AGUIRRE | | | SCAC4 |
| 26 | MFAR | MANHEIM FARM | | | SCAC4 |
| 27 | MFAS | MFA-FAST EXPRESS | | | SCAC4 |
| 28 | MFAX | Producers Produce Co. (Merchants Despatch, Inc.) | 7/1935 | | NAKINA |
| 29 | MFAX | M.F.A. Egg & Poultry Association | 7/1932 | | NAKINA |
| 30 | MFAX | M.F.A. EGG & POULTRY ASSOCIATION | | | PWRC |
| 31 | MFAZ | MFA INDUSTRIES | | | PWRC |
| 32 | MFB | Mountain Flyers 80 Ltd | Callsign: Mountainheli, | CH | AVCODES |
| 33 | MFB | Mainische Feldbahn Schwerte | Schwerte | D | privat-bahn.de |
| 34 | MFBE | MORIN FORESTRY & BOSSE TIMBER INC | | | SCAC4 |
| 35 | MFBG | MAGNUM FABRICATING LTD | | | SCAC4 |
| 36 | MFBK | MOUNTAIN FREIGHT BROKERAGE INC | | | SCAC4 |
| 37 | MFBL | MFB | | | SCAC4 |
| 38 | MFC | Moncton Flying Club | Callsign: East Wind, Name changed to Canlink Aviation Inc. | CDN | AVCODES |
| 39 | MFC | Canlink Aviation Inc. | Callsign: East Wind, Name changed from Moncton Flying Club | CDN | AVCODES |
| 40 | MFC | Moncton Flying Club | | | ICAO1 |
| 41 | MFCD | MARLO FURNITURE CO INC | | | SCAC4 |
| 42 | MFCE | MEGA FLEET CORP | | | SCAC4 |
| 43 | MFCH | MAGNUM FREIGHT CORP | | | SCAC4 |
| 44 | MFCJ | MARMOL FREIGHT CORP | | | SCAC4 |
| 45 | MFCK | MS FREIGHT CO INC | | | SCAC4 |
| 46 | MFCL | MFC LOGISTICS CORP | | | SCAC4 |
| 47 | MFCO | MILLIS TRANSFER INC (DEDICATED DIVI | | | SCAC4 |
| 48 | MFCQ | MATTSEA FISH COMPANY LTD | | | SCAC4 |
| 49 | MFCU | FINSTERWALDER CONTAINER GMBH | | D | BIC |
| 50 | MFCV | MADEFERRETERA CASTOR SA DE CV | | | SCAC4 |
| 51 | MFCW | MILLER, FRED CUSTOM WOODWORKS | | | SCAC4 |
| 52 | MFCX | First Union Rail | added 10/1996; 7/2000-7/2005 | | NAKINA |
| 53 | MFCX | USL Capital Rail Services | added 4/1994; eliminated 10/1996 | | NAKINA |
| 54 | MFCX | U.S. Rail Services, Inc. | added 4/1993; 1/1994; eliminated 4/1994 | | NAKINA |
| 55 | MFCX | Chrysler Rail Transportation Corp. | eliminated 4/1993 | | NAKINA |
| 56 | MFCX | Farmers Coop Grain and Supply Co. | added 7/1980; eliminated 4/1989 | | NAKINA |
| 57 | MFCX | Marfax Steel and Railway Equipment Co. | added 10/1967; 4/1970; eliminated 7/1970 | | NAKINA |
| 58 | MFCX | Marfax Steel and Railway Equipment Co. | added 10/67; 4/70; eliminated 7/70 | | NRHS |
| 59 | MFCX | Farmers Coop Grain and Supply Co. | added 7/80; eliminated 4/89 | | NRHS |
| 60 | MFCX | Chrysler Rail Transportation Corp. | eliminated 4/93 | | NRHS |
| 61 | MFCX | U.S. Rail Services, Inc. | added 4/93; 1/94; eliminated 4/94 | | NRHS |
| 62 | MFCX | USL Capital Rail Services | added 4/94; eliminated 10/96 | | NRHS |
| 63 | MFCX | First Union Rail | added 10/96; 7/2000 | | NRHS |
| 64 | MFCX | *MARFAX STEEL & RAILWAY EQUIPMENT CO. | | | PWRC |
| 65 | MFCX | *(RUSX) USL CAPITAL RAIL SERVICES [FARMERS CO-OP GRAIN & SUPPLY] | | | PWRC |
| 66 | MFCX | +FIRST UNION RAIL {USL CAPITAL RAIL SERVICES; U.S. RAIL SERVICES, INC.; CHRYSLER RAIL TRANSPORTATION CORP.] | | | PWRC |
| 67 | MFCX | Farmers Coop Grain and Supply (First Union Rail) | | | RSRV |
| 68 | MFCY | MILICEVIC FREIGHT COMPANY | | | SCAC4 |
| 69 | MFD | Monarch Air Group, LLC | Callsign: Freight Dog, | USA | AVCODES |
| 70 | MFDC | MARSHFIELD DRAYAGE COMPANY | | | SCAC1 |
| 71 | MFDO | MOFFAT, DENTON | | | SCAC4 |
| 72 | MFDP | MCFARLAND TRUCKING | | | SCAC4 |
| 73 | MFDQ | MF DRAKE TRANSPORT LLC | | | SCAC4 |
| 74 | MFDS | MILLER, FDS CARTAGE | | | SCAC4 |
| 75 | MFDW | MARITTIMA FLUVIALE DI NAVIGAZIONE S | | | SCAC4 |
| 76 | MFEC | MAPLE LEAF CONSUMER FOODS INC | | | SCAC4 |
| 77 | MFED | MILLSON FORESTRY SERVICES | | | SCAC4 |
| 78 | MFEG | MCFEETERS, G ENTERPRISES INC | | | SCAC4 |
| 79 | MFEM | MAYER FARM EQUIPMENT | | | SCAC4 |
| 80 | MFEP | MAPLE FARM EQUIPMENT | | | SCAC4 |
| 81 | MFEQ | MCGRAIL FARM EQUIPMENT LIMITED PART | | | SCAC4 |
| 82 | MFER | MASTER TRANSFER CO INC | | | SCAC4 |
| 83 | MFER | Materfer: Material Ferroviario S.A. | | RA | TRAFFIC |
| 84 | MFERS | M. FERRICOS9, S.L. | | ES | VKM |
| 85 | MFET | MAYER FARM EQUIPMENT INC | | | SCAC4 |
| 86 | MFFA | MIAMI FOLIAGE FORWARDERS INC | | | SCAC4 |
| 87 | MFFC | MIDWEST FRT FWDG CO INC | | | PWRC |
| 88 | MFFE | Großherzoglich Mecklenburgische Friedrich Franz Eisenbahn | | D | TRAFFIC |
| 89 | MFFF | MARTINS FAMILY FRUIT FARM LTD | | | SCAC4 |
| 90 | MFFI | MOBILIA FRUIT FARMS INC | | | SCAC4 |
| 91 | MFFO | MAYFAIR FUEL OIL CO | | | SCAC4 |
| 92 | MFFS | MEYERS FLOWERS | | | SCAC4 |
| 93 | MFFT | MOFFITT DODGE CHRYSLER LTD | | | SCAC4 |
| 94 | MFFV | M.R.S. FREIGHT FORWARDING SERVICES, INC | | | SCAC1 |
| 95 | MFFX | M4 Holdings Ltd. | added 4/1985; eliminated 1/1992; 1/1994-7/2005 (not listed) | | NAKINA |
| 96 | MFFX | Midwestern Farm Fertilizers, Inc. | 4/1961 (not listed); added 1/1963; 7/1965; eliminated 10/1965 | | NAKINA |
| 97 | MFFX | Midwestern Farm Fertilizers, Inc. | 4/61-7/65; eliminated 10/65 | | NRHS |
| 98 | MFFX | M4 Holdings Ltd. | added 4/85; eliminated 1/92; 1/94-7/2000 | | NRHS |
| 99 | MFFX | *MIDWESTERN FARM FERTILIZERS, INC. | | | PWRC |
| 100 | MFFX | +M4 HOLDINGS LTD. | | | PWRC |
