Banknotes have constituted the chief means of payment for about 200 years. As such, they are subject to the inevitable risks of wear and soiling, of falsification through alteration of the face value, and of counterfeiting on an international level. To reduce these dangers, the issuing agencies must choose long-lasting materials, colors and designs which are difficult to imitate, and special features such as colored fibers in the paper. Victims are members of the public who lose the face value of the bill and the state whose credit is undermined. The dangerousness of the counterfeit bill depends on the protection and quality of the original, the quality of the imitation, and the level of knowledge and degree of attention of the public. Bills must be readily identifiable as belonging to a certain country and having a certain value. For both practical and aesthetic reasons, they must have a clear, nationally oriented motif which is interesting and easy to remember; the same type of bill should not be kept in circulation too long. Principal elements to be considered in printing bills are fonts used, the motif, decorations, administrative texts, and elements permitting electronic sorting. Expensive printing processes are difficult to reproduce and therefore preferable to offset; authentic bills must be absolutely consistent in their details. The public should be informed of details like paper feel, design significance, and printing techniques for each bill. School programs for children over 10 years old can aid in such efforts. Bills should not be too small or of too small a denomination, because the public will have trouble remembering them. Emphasis should be placed on visible distinguishing characteristics but secret identifying marks (e.g., fluorescence under ultraviolet lights) must also be included. Several notes and an 8-item bibliography are supplied.--in French.