travelling in OPT

I have been offered Canadian permanent residency. And I am going to Canada in a few months for to establish his residency. But I need to come to defend my thesis in next Fall. I am going to be on OPT in the meanwhile. Before going to Canada.

The question is, will the INS allow me to come back for sure to defend my thesis when it finds me on EAD on the basis of OPT ?

Thank you.

I have been offered Canadian permanent residency. And I am going to Canada in a few months for to establish his residency. But I need to come to defend my thesis in next Fall. I am going to be on OPT in the meanwhile. Before going to Canada.

The question is, will the INS allow me to come back for sure to defend my thesis when it finds me on EAD on the basis of OPT ?

Thank you.

You can leave but remember that on F-1 you are allowed to leave the US for up to 5 months if you plan to come back on same I-20 (problably you'll only need to apply for a new F1 visa to come back). If you stay out for more than 5 Mos. you'll have to apply for another I-20 to come back into the US as student which will be a little more complicated to get. Besides, on new I-20 you'll start from the bottom again and will loose your OPT. In short: as long as you go and come back before the 5 months deadline, you should be OK.
Good Luck!

I don't think there is any problem here as canadian Permanent resident have access to the US without any problem.as long as you are a Canadian permanent resident you don't even need a visa to enter the US for a Short period of time ( 3months)

To come back to the U.S. from Canada, you don't need a valid visa, as long as you don't stay for more than 30 days. However, you need to have legal status here, so you'll need to bring your I-20 and all the documents that prove your status here in the U.S. This is called the automatic revalidation of visa. The passport should also have a visa stamp, expired or current. Note, the above is for anybody who's legal in the U.S. I believe for Canadian PR it should be easier.