Software development is a knowledge-intensive task, with an increasing demand for higher productivity. During the design phase,
the use of visual modelling languages like UML (Unified Modeling Language) are wide spread across the software industry. In
this paper we present a CBR tool that helps the software engineers to reuse UML diagrams. We describe our system, REBUILDER
UML, and present experimental work showing that our system decreases the number of errors made by software engineers during
the design of UML diagrams.