Amex is the 3rd most popular credit card in the United States. Many businesses don't accept American Express because they feel the fees are too high. In truth they usually are no higher and could be lower than accepting a Visa coporate card. Chances are if a customer gives you an Amex it's because he wants the bonuses the card offers and may very well take his business elsewhere. You can decide for yourself if you would like to turn away that customer.