| Radio Engineering Industries | Academic & Science |
| Renta Electronic Invoice | Academic & Science |
| Research Engineers International | Academic & Science |
| Research Electronics International | Academic & Science |
| Requirement for Electrical Installation | Academic & Science |
| Regina | Airport Code |
| RioCan Real Estate Investment Trust | Business |
| Real Estate Investment | Business |
| Reliant Energy, Inc. | Business |
| Recreational Equipment, Inc. | Business |
| Reaction Engineering International | Business |
| Real Estate Investing | Business |
| Rochester Electronics, Incorporated | Business |
| Real Estate Investments | Business |
| Regular Education Initiative | Community |
| Research and Educational Institute | Community |
| Reading Every Index | Community |
| Resources in Education Index | Community |
| Reset Indication | Computing |
| Remote Error Indicator | Computing |
| Red de Empresas de Internet | Computing |
| Zerogoki | Cryptocurrency |
| Return Every Item | General |
| Return Equipment Immediately | General |
| Real Equipment Impossible | General |
| Rhythmic Entrainment Intervention | General |
| Real Expensive Items | General |
| Really Expensive Items | General |
| Reliable Effective and Innovative | General |
| Release Eligible Inmate | General |
| Reproductive Endocrinology and Infertility | General |
| Restrictive Entry Intervals | General |
| Rain Eri Isabel | General |
| Recommended Exposure Index | General |
| Reproductive Endocrinology Infertility | General |
| Renewable Energy International | General |
| Ring Energy Inc | Governmental |
| Rutgers Energy Institute | Governmental |
| Racial Equity Institute | Governmental |
| RITHI | Indian Railway Station |
| Radio España Independiente | International |
| Recreational Equipment International | International |
| Resource Exchange International | International |
| Recreational Equipment Incorporated | Messaging |
| Restricted Entry Interval | Military and Defence |
| Regina, French Guiana | Regional |
| Range From Entry Interface (400 K) | Space Science |
| Runway End Identification | Space Science |
| Re Entry Interval | Space Science |
