I had to find this the extremely hard way. Paypal kept sending me to a list of countries that PayPal works in, but it was more geared towards the individual and not someone that has Website Payments Pro account like we did.

I got this list by logging in, going to My Account. I then went to Fraud Management and clicked the link at the bottom to configure my filters (un-conveniently located at the bottom of the page). I clicked on Edit for the Country Monitor filters. And there was a list of countries, so I figured that these are the countries that can be accepted.

I changed the filter to Flag so that it will accept it but flag it for later. This way we wouldn't miss any transactions, they would just be flagged.