- Aboriginal & First Nations Organizations
- Abortion Alternatives
- Abortion Clinics & Services
- Abrasives
- Accountants
- Accounting Services
- Acoustic Consultants
- Acoustic Materials
- Acoustical Contractors
- Acoustical Engineers
- Actuary Consulting & Services
- Acupuncturist Equipment & Supplies
- Acupuncturists
- Ad Production
- Adaptive Clothing
- Addiction Treatments & Information
- Addressing & Letter Service
- Adhesive Tapes
- Adhesives & Glues
- Adoption Agencies & Services
- Adult Entertainment
- Adventure Games & Activities
- Advertising Agencies
- Aerial Advertising
- Aerial Photographers
- Aerial Seeding & Spraying Service
- Aerial Surveyors
- African Restaurants
- Agricultural Chemicals
- Agricultural Consultants
- Air & Water Systems Balancing
- Air Cargo Service
- Air Conditioning Contractors
- Air Conditioning Repair & Cleaning
- Air Conditioning Systems & Parts
- Air Pollution Control
- Air Pollution Measuring Equipment & Service
- Air Purifiers
- Air Quality Services
- Air Sports
- Airbrushing
- Aircraft & Flight Schools
- Aircraft & Private Jet Charter
- Aircraft Dealers
- Aircraft Design & Manufacturers
- Airline Ticket Agencies
- Airlines
- Airport Parking
- Airport Transportation Service
- Airports
- All-Terrain Vehicles
- Allergy Medications & Services
- Alternative Health
- Alternators & Starters
- Aluminum
- Aluminum Fabricators
- Aluminum Products
- Ambulance Service
- Ambulances & Hearses
- American Restaurants
- Amusement Machines & Supplies
- Amusement Places
- Analytical & Testing Laboratories
- Animal Breeders
- Animal Medications
- Animal Shelters & Protection Services
- Annuities
- Anodizing
- Answering Machines & Equipment
- Antennas
- Antique & Classic Cars
- Antique Dealers
- Antique Reproductions
- Apartment Hotels
- Apartment Rental
- Apartments
- Appliance Manufacturers & Wholesalers
- Appliance Parts & Supplies
- Appliance Repair & Service
- Appraisers
- Aptitude Testing
- Aquaculture
- Aquariums & Supplies
- Arbitration Service
- Arcades
- Archaeologists
- Archery & Crossbows
- Architect Supplies
- Architects
- Architectural & Construction Specifications
- Architectural Drawing
- Architectural Technologists
- Archives
- Armoured Cars
- Aromatherapy
- Art Foundries
- Art Materials & Supplies
- Art Metal Work
- Art Publishers & Distributors
- Art Restorations
- Art Schools
- Artificial Flower & Plant Arrangements
- Artificial Flower & Plant Manufacturers & Wholesalers
- Artificial Insemination
- Artificial Limbs
- Artists
- Arts & Crafts Classes & Schools
- Arts & Crafts Manufacturers & Wholesalers
- Arts & Crafts Markets
- Arts & Crafts Stores
- Arts & Crafts Supplies
- Arts & Cultural Organizations & Centres
- Asbestos Products
- Asbestos Removal & Abatement
- Asbestos Testing & Consultants
- Asian Noodle Restaurants
- Asian Products
- Asian Restaurants
- Asphalt Products
- Assayers
- Assembly & Fabricating Services
- Assisted Living
- Association Management
- Associations
- Astrologers & Psychics
- Astronomy
- Auctions
- Audiologists
- Audiometers
- Audiovisual Consultants
- Audiovisual Equipment & Supplies
- Audiovisual Equipment & Supplies Rental
- Audiovisual Production Services
- Auditoriums & Halls
- Auto Body Repair & Painting Shops
- Auto Body Shop Equipment & Supplies
- Auto Diagnostic
- Auto Glass & Windshields
- Auto Part Manufacturers & Wholesalers
- Auto Repair Garages
- Auto Repair Self Service Garages
- Automated Teller Manufacturers & Wholesalers
- Automatic Fire Sprinkler Systems
- Automation Consultants
- Automation Systems & Equipment
- Automotive Springs
- Aviation Consultants & Services
- Awning & Canopy Cleaning Service
- Awning & Canopy Manufacturers & Wholesalers
- Awning & Canopy Sales & Service
- Axles