Abstract. Design patterns already proved successful in lowering the development time and number of errors of object-oriented software; now, they are, candidate to play a similar role in the MAS (multi-agent system) context. In this work we describe our experiences in the identification, production and application of patterns for agents. Some patterns are described together with the classification criteria and documentation approach we adopt. Upon them, we base a pattern reuse process that can be considered one of the distinguishing elements of the design methodology (PASSI) we use to develop MAS. Patterns can be applied to an existing agent or used to produce a new one with the support of a specific web based application that can read both the JAVA source code and XMI representation of the agent design documentation. After the successful application of the desired pattern(s), the source code and the design diagrams (usually a structural and dynamic diagram) of the agent can be expor...