If you are a temporary foreign worker presently in Canada, and wish to leave for a short time (for example, to visit your home country) and then return to Canada, you should be aware of the following:
If you require a visa to enter Canada and a work permit to legally work, you may only re-enter Canada to work as long as both your visa and work permit are still valid when you return. Your passport must also be valid.
If your visa has expired but the work permit is still valid, you must apply for another temporary resident visa to return to Canada. If your work permit has expired, but your visa is still valid, you will need to apply for a new work permit. In both cases, you must apply for either a visa or a work permit at a visa office outside Canada before returning to Canada.
Your temporary resident visa, work permit and passport all need to be valid if you want to return to Canada to work. Otherwise you may be refused entry to Canada.
If you do not require a temporary resident visa because you are a national of a visa-exempt country and you wish to return to Canada to work, you must have a valid work permit and passport when you return.
If your work permit has expired you will need to apply for a new work permit at a visa office outside of Canada before returning to Canada. You will also require a valid passport. Otherwise you may be refused entry to Canada.