Traveler's Checks -- Citibank will exchange its own traveler's checks. But you can't change American Express traveler's checks at the American Express offices in Bolivia (sounds strange, but it's true). If you're traveling with traveler's checks, your best bet is to cash them at a casa de cambio. Most upscale hotels and restaurants in Bolivia will accept traveler's checks. For lost American Express traveler's checks, you must call collect to the United States at tel. 801/964-6665. 

Credit Cards -- MasterCard and Visa are accepted most everywhere in Bolivia. American Express is less common, but it's still widely accepted. To report a lost or stolen MasterCard, call tel. 0800-0172; for Visa, tel. 0800-0188; for American Express, call tel. 800/327-1267 (via an AT&T operator).