| Abbreviation | Definition |
|---|---|
| MCS | Morts Computer Solutions |
| MCSA | Media Control Services Australia |
| MCSC | Merrillville Community School Corporation |
| MCSF | Marine Corp Scholarship Foundation |
| MCSI | Managed Care Systems INC |
| MCSI | Managed Care Systems, Inc. |
| MCSI | Mays Construction Specialties Inc |
| MCSI | Mechanical Contracting Services Inc |
| MCSI | Michigan Community Services Inc |
| MCSI | Mike Cindia Sales Inc |
| MCSI | Millerstown Community Success Inc |
| MCSI | Mining Consulting Services, Inc. |
| MCSI | Minnesota Computer Systems Inc |
| MCSI | Mission Critical Solutions Inc |
| MCSI | Molli Computer Services, Inc. |
| MCSI | Moore Control Systems Inc |
| MCSI | Morgan Stanley Capital International |
| MCSI | Motorola Cellular Services Inc |
| MCSI | Municipal Collection Services Inc |
| MCSP | Mayfair Computer Software and Peripherals |