In object-oriented database systems (OODBSs), the traditional transaction models are no longer suitable because of the difference between the object-oriented data model (OODM) and the conventional data models (e.g. relational data model). In this paper, transaction models for advanced database applications are reviewed and their shortcomings are analyzed. Exchangeability of operations is proposed instead of commuativity and recoverability for using more semantics in transaction management. As a result, an object-oriented transaction model (in short, OOTM) is presented. It is not modeled for some special application, but directly based on object-oriented paradigms. A transaction is regarded as an interpretation of a method. Each transaction (even subtransactions) keeps relative ACID (Atomicity, Consistency, Isolation, Durability) properties, therefore the special problems appearing in OODBSs such as “long transactions”, “visibility of inconsistent database state” can be solved.