Keep a reasonable amount of cash in your wallet as travellers' cheques can only be exchanged at authorised foreign banks, mostly in the large Vietnamese cities. In HCMC, Vietcombank at 8 Nguyen Hue, ACB at 30 Mac Dinh Chi and ANZ Bank at 39 Le Duan will all exchange travellers' cheques. Most banks will charge a commission of around 2%, but the fee can be lower or higher depending on the type of currency being exchanged.
With the growing number of ATMs in Ho Chi Minh City, it is becoming less common for visitors to carry travellers' cheques. If you plan to cash travellers' cheques at one of the authorised foreign banks in Saigon, make sure to bring your passport and any other ID. It is worth noting that Vietcombank will not levy an exchange fee on American Express travellers' cheques.