1) Canadian Trademark Registry
The Canadian government maintains a registry of trademarks, which can be accessed through the federal government’s Strategis website.
2) Corporate & Business Name Registries
These searches concentrate on the federal and provincial government registries for business names. Most such important public registries are now available on the Internet, but you will have to go to 12-15 different sites and search each one. The Canadian Intellectual Property Office (CIPO) maintains a page with links to registrars’ sites
Click here for the CIPO home page
3) U.S. Trademark Registry
The U.S. Patent & Trademark Office (known as the USPTO) maintains a link to the U.S. federal trademark database for search purposes. This is useful to search even if you aren’t planning an using the trademark in the U.S. Sometimes, U.S. trademarks can ‘leak’ across the border, creating common-law rights in Canada.
4) Search Engines & Other Sources
Since a trademark does not have to be registered in order to be valid, you should search for unregistered trademarks as well. Your least expensive and first search for exact matches should be an Internet search. Other good sources to search are libraries, trade journals, business directories, magazines and newspapers, which can be found both on-line and off.