An indicator flag for attachment to a mailbox for indicating the presence of mail therein uses a generally horizontally disposed flag member that is rotatably attached to the door of the mailbox and that rotates between a first position wherein the flag member is generally flush against the mailbox door, indicating an absence of mail for pickup, and a second position wherein the flag member extends generally horizontally outwardly from the door, indicating the presence of mail therein for pickup. A mail carrier can easily rotate the flag member back to the first position with the same motion used to open the mailbox door.