: This paper describes the development of an open source CASE tool, the ArgoCASEGEO, and its modular architecture. The ArgoCASEGEO allows the geographic database modelling based on the UML-GeoFrame conceptual model that is specific for Geographic Information Systems applications. The data dictionary associated to the modelled schema is stored as a XML/XMI document, aiming its use by other software. The ArgoCASEGEO follows a design methodology based on a reusable collection of analysis patterns. The analysis patterns collection is stored in a data base composing a Catalog. The catalog is attached to the ArgoCASEGEO. Thus, searching for existing analysis patterns will be an easier and efficient task. Key words: Geographic database design, Analysis Patterns, CASE tool.