If you are a lawful permanent resident you can travel with the green card. MAke sure you also have a current passport and you are eligible to travel to Canada. Canada's rules are different and depending where you are from, you may or may not need a visa to enter Canada.
Mr. Lorenzon's answer to your question does not establish an attorney client relationship, but rather is meant to share knowledge with the general public. For specific advise on your case, you need to consult one on one with an immigration attorney. Mr. Lorenzon can be reached at 216 573 7322 or at firstname.lastname@example.org. All initial constulations are free.
If you have a valid passport and green card, you can travel. Never stay out for than 6 months
Neil I Fleischer (513) 977-4209 www.immigrate2usa.com Note: Neil Fleischer is an attorney licensed in the State of Ohio The below answer is provided for informational use only. One should not act or refrain to act solely based on the information provided. No attorney/client relationship is created unless an Agreement is signed by the attorney and the client. Best regards, Neil Neil I Fleischer The Fleischer Law Firm, LLC 917 Main Street Cincinnati, Ohio 45202-1314 Direct telephone: 513 977 4209 email@example.com Enjoy our Blog at http://immigrate2usa.blogspot.com/