Permanent residents should always have a permanent resident card (PR card) as a basic document to demonstrate that they possess permanent residence status in Canada.  It is important to renew your PR Card before it expires, as international airlines generally ensure that passengers who are permanent residents of Canada present one before allowing boarding.  If you find that you are outside Canada with no or an expired PR card, you will likely need a Permanent Resident Travel Document (PRTD) to return to Canada.  This application is made at the Canadian visa office closest to you and requires you to provide forms detailing your absences from Canada as well as supporting documents.  If you have any concerns about whether you meet the residence requirement (2 years of residence in each 5-year period), or if you are not certain whether your documents are sufficient, you should obtain legal advice prior to applying.  PRTD applications are very similar to PR card renewals and officers scrutinize applications very carefully.  If you are found to have failed to meet the residence requirement, not only can an officer refuse the PRTD, but also determine that you are no longer a permanent resident. If this happens, you may be able to file a Residence Appeal. We can advise you whether there is any risk, and if so, how to mitigate it.