| Mail Receiving Service | 277 |
| Mailing Services | 277 |
| Make-Up Services | 277 |
| Management Consultants | 277 |
| Management Training | 277 |
| Manufacturers’ Agents & Representatives | 277 |
| Marble & Terrazzo Cleaning & Service | 277 |
| Marble Contractors | 277 |
| Marble-Cultured | 277 |
| Marble-Natural | 277 |
| Mardi Gras Supplies & Services | 278 |
| Marinas | 278 |
| Marine Contractors | 278 |
| Marine Electronics | 278 |
| Marine Equipment & Supplies | 278 |
| Marine Equipment & Supplies-Whsle & Mfrs | 278 |
| Marine Resource Consultants | 278 |
| Marine Surveyors & Adjustors | 278 |
| Market Research & Analysis | 278 |
| Marketing Consultants | 278 |
| Marketing Programs & Services | 279 |
| Markets-Public | 279 |
| Marriage, Family, Child & Individual Counselors | 279 |
| Masonry Contractors | 279 |
| Masonry Equipment & Supplies | 279 |
| Massage Therapists | 279 |
| Massages | 279 |
| Mastectomy Apparel, Forms & Prostheses | 280 |
| Material Handling Equipment | 280 |
| Maternity Apparel | 280 |
| Maternity Services | 280 |
| Mattresses | 280 |
| Mattresses-Renovating | 280 |
| Mausoleums | 280 |
| Meat | 280 |
| Meat Markets-Specialty | 280 |
| Meat-Whsle | 280 |
| Mechanical Contractors | 280 |
| Media Brokers | 280 |
| Mediation Services | 280 |
| Medical & Dental Business Consultants | 281 |
| Medical Business Administration | 281 |
| Medical Equipment & Supplies | 281 |
| Medical Examinations-Insurance | 281 |
| Medical Information Services | 281 |
| Medical Service Organizations | 281 |
| Medical Services | 281 |
| Meditation Instruction | 281 |
| Men’s Clothing & Furnishings | 281 |
| Mental Health Services | 282 |
| Mental Retardation & Developmentally Disabled | 282 |
| Services |
| Messenger Service | 282 |
| Metal Cleaning | 282 |
| Metal Fabricators | 282 |
| Metal Finishers | 282 |
| Metal Specialties | 282 |
| Meteorological Consultants | 282 |
| Meters | 282 |
| Microwave Ovens-Service & Repair | 283 |
| Millwork | 283 |
| Mining Companies | 283 |
| Mirrors | 283 |