Originally Posted by
Embuexpat
I'm not up to date with the formalities as I now travel on UK/Brazilian passports. However, would the PF not wish to see an entry stamp on the passport presented for exit? Also the Cartão De Entrada/Saida details would be different?
That 's not what the poster was saying. You show both passports to the airline when leaving the US ( so they know you can enter and they will not have to return you to point of departure at their expense). You enter and leave Brazil on the UK passport, which does not require a Brazilian visa, and receives a 90 day prazo on entry. On leaving Brazil, the airline at the airport in Brazil will probably not ask about visa status for the US, but if so, just show the US passport. You re- enter the US on the US passport.