Business rules are an important element of information systems. The notion business rule encompasses different phenomena; therefore, some classification criteria are presented and several examples are introduced to demonstrate different types of business rules. Given their practical importance, the necessity of a consistent treatment in the life-cycle of information systems is obvious. Therefore, commonly used function- and data-oriented methodologies for systems analysis are examined with respect to their ability to express business rules. It is shown that common methods are insufficient or at least inconvenient for a complete and systematic modeling of business rules. Some relevant enhancements of these methods are more powerful but still emphasize only certain aspects and types of business rules. Keyword Codes: D.2.1; H.2.m