| MAJ MBQ MCP MDL MDO MEF MEH MER MEV MFJ MFO MFR MFT MGF MGH MGQ MGX MHD MHE MHF MHJ MHL MHO MHU MHV MHX MID MIH MIK MIR MIY MJA MJW MJY MJZ MKF MKN MKQ MKX MLB MLC MLD MLS MLW MNI MNL MNM MNO MOA MOB MOH MOL MOM MON MOO MOP MOT MOX MOZ MPK MPZ MQB MQC MQF MQG MQM MQN MQP MQS MQT MQY MRA MRB MRD MRI MRO MSL MSO MSX MTG MTJ MTK MTL MTM MTQ MUI MUL MUU MVC MVI MVS MVW MWB MWC MWI MWQ MWS MWT MWY MXB MXC MXG MXJ MXT MXX MYA MYC MYJ MYO MYP MYV MZF MZS MZV | Alpha Prefix not assigned or unallocated |
| MAP MBB MJB | Anthem Blue Cross Blue Shield of Colorado |
| MAW MJO MXU | Anthem Blue Cross Blue Shield of Connecticut |
| MAR MAS MBF MCI MEG MFC MFD MFH MFM MGS MHI MHQ MMC MMP MOC MPB MPS MPV MQE MTF MVK MXS | Anthem Blue Cross Blue Shield of Georgia |
| MAE MBP MCZ MDJ MED MMQ MMY MTV MUJ MVU | Anthem Blue Cross Blue Shield of Indiana |
| MAK MHS MNS MOW | Anthem Blue Cross Blue Shield of Kentucky |
| MAN MEB MEN MEP MEW MEY | Anthem Blue Cross Blue Shield of Maine |
| MBT MGJ | Anthem Blue Cross Blue Shield of Missouri |
| MWW | Anthem Blue Cross Blue Shield of Nevada |
| MAV MBA MBW MFG MHN MHR MIF MIQ MIS MKG MKJ MMS MMV MNJ MNK MOJ MPA MPU MPW MRQ MSN MSU MTW MVY MYE MYM MYN | Anthem Blue Cross Blue Shield of Ohio |
| MAH MCO MCY MEC MEE MFN MFQ MGU MLK MLP MNH MSS MTA MTC MUB MZK | Anthem Blue Cross Blue Shield of Virginia |
| MDN MDR MJH MJT MJV MND MNE MPP MQU MRH MRN MRP MRX MUF MUK MUO MWE MWM MWU MWV MZJ | Anthem Blue Cross Blue Shield of Wisconsin |
| MBL MBR MDE MFE MFW MHG MHY MJL MJQ MKK MNC MPI MPR MQX MQZ MRV MSZ MTY MXA MXR | Anthem Bluecross of California |
| MCM MGW MOV MUG | Arkansas Blue Cross Blue Shield |
| MBG MBH MHW MJD MMX MPO MRY MSA MSC MSV MUY MVM MWX MYR MZL | Blue Cross Blue Shield of Alabama |
| MUM MZH | Blue Cross Blue Shield of Arizona |
| MAX MBM MCD MCQ MDX MFA MFV MFZ MGC MKR MLE MMK MML MMU MMW MNT MNX MOE MPL MRC MRG MRW MRZ MSW MTZ MUN MUS MWA MWF MWH MWL MWN MZD MZG | Blue Cross Blue Shield of Illinois |
| MCB MDY MHA MII MRM MWR | Blue Cross Blue Shield of Kansas City |
| MDV | Blue Cross Blue Shield of Louisiana |
| MBU MCX MIL MKD MKS MLR MMR MNB MOD MOI MRK MSK MTN MTP MVE MVL MWP MXN MXP MXY MYD MYH MYI MYK MYL MYQ MYS MYU MYZ MZE | Blue Cross Blue Shield of Massachusetts |
| MBI MBN MDA MDG MEI MFX MGO MGR MHH MIG MIJ MIW MJE MJJ MJR MJU MJX MKO MKP MMJ MMO MOU MPE MQA MQH MQJ MQK MQL MQO MQW MRF MSE MSG MSH MSR MUR MUZ MYT MZO MZP MZY | Blue Cross Blue Shield of Michigan |
| MDC MDQ MDZ MFY MIB MIE MLQ MLU MLV MMM MMN MNA MNQ MNR MPQ MPT MPX MRR MUT MVG MVT MWG MZM MZQ MZR MZT MZW MZX MZZ | Blue Cross Blue Shield of Minnesota |
| MKL MMG | Blue Cross Blue Shield of Mississippi |
| MVA | Blue Cross Blue Shield of Montana |
| MAY MBE MET MLT MQV | Blue Cross Blue Shield of Nebraska |
| MAG MEX MEZ | Blue Cross Blue Shield of New Mexico |
| MCU MDK MNU MSY MZN | Blue Cross Blue Shield of North Carolina |
| MES MYX | Blue Cross Blue Shield of Oklahoma |
| MDH MGE MLZ MPC MZC | Blue Cross Blue Shield of Rhode Island |
| MBX MBY MDB MGN MGV MIC MIU MKC MLH MNV MPJ MUP MVX | Blue Cross Blue Shield of South Carolina |
| MBC MJS MKE MKH MKI MNG MTR | Blue Cross Blue Shield of Tennessee |
| MAT MCC MEU MHB MJC MPD MRT MUA MVZ MXD MXE | Blue Cross Blue Shield of Texas |
| MVB | Blue Cross Blue Shield of Vermont |
| MIV MLO MOG | Blue Cross Blue Shield of Western New York |
| MIP MLX MQQ MUH MVO MVQ MXV MXW | Bluecross of Idaho |
| MCA MDP MEA MEK MEO MEQ MGA MGG MGY MIA MIO MIX MIZ MKB MLL MLN MMT MNP MOF MOS MTE MTI MTO MTT MVJ MXI MZI | Blueshield of California |
| MPM | Blueshield of Northeastern New York |
| MGB MXK | Capital Bluecross of Pennsylvania |
| MAC MAF MAL MAM MBD MBS MBV MBZ MCF MCG MCR MCS MDD MDM MDS MDT MEJ MFK MFS MGM MHM MHT MJF MJI MJK MKM MKZ MLF MLJ MMB MME MQD MRJ MSM MTS MTX MUV MVP MWD MXH MYW MYY | Carefirst Blue Cross Blue Shield(Maryland/District of Columbia/Northern Virginia) |
| MBK MHP MMA MMH MPH MSF MVF MVN MXF MXQ MYF | Empire Blue Cross Blue Shield of New York |
| MMF MPF | Excellus Blue Cross Blue Shield of New York |
| MAB MAO MAQ MBO MCH MPY MZU | Florida Blue |
| MGI MHC MIM MJM MJN MLG MLM MNN MQR MRU MUW MVR MZB | Highmark Blue Cross Blue Shield of Pennsylvania |
| MCJ | Highmark Blue Cross Blue Shield of West Virginia |
| MGZ MKV MKY MWJ MWK | Horizon Blue Cross Blue Shield of New Jersey |
| MDF MFL MGL MLI MMI MNF MOK MOQ MPG MSD MWO MWZ | Independence Bluecross of Philadelphia and Southeastern Pennsylvania |
| MAD MCE MGD MIN MJG MKU MLY MMD MNW MOR MSJ MSP MSQ MST MTD MVD MXZ | Premera Blue Cross Blue Shield of Alaska |
| MNY MTU MUQ | Premera Bluecross of Alaska |
| MBJ MFF MFP MGT MSI MYB | Regence Blue Cross Blue Shield(Oregon/Idaho/Utah/Washington) |
| MAA MAI MAU MAZ MCK MCL MCN MCT MCV MCW MDI MDU MDW MEL MEM MFB MFI MFU MGK MGP MHK MHZ MIT MJP MKA MKT MKW MLA MMZ MNZ MOY MPN MQI MRE MRL MRS MSB MTB MTH MUC MUD MUE MUX MVH MVV MXL MXM MXO MYG MZA | Wellmark Blue Cross Blue Shield of South Dakota/Iowa |