I've seen a thread on this (not sure where). The only school that I know of that accepts US citizens is McGill, and it is VERY competitive (like a mid to upper-tier US MD program).
I hope that helps...
Canadian med schools are really hard to get accepted to - mainly because there are so few schools and way to many Canadians wanting to go the med school. Alot of Canadian applicants are actually forced to come to the US to go to med school because of all the competition - I'd say it's not a great idea to consider Canadian schools - they are just too competitive (number of people applying-wise)
McGill does accept American students, but I believe it is the only school is Canada that does. If you have Canadian citizenship you will be able to apply to other Canadian schools, but I believe the requirements on average are higher than American schools.
my friend from Canada is only applying to US schools because it is sooo competitive in Canada. She atcually told me a friend of hers with a 35 still did not get accepted into any canadian med schools...i hope that gives you some perspective
Dalhousi also accepts US citizens.. UofToronto also accepts international applicants.
Unless you have exceptional reasons/and grades.. I would not even bother applying to Canada. I am actually coming down to US to study.