In this work we present SIMA (System for distributed IMage Applications), a tool for contructing distributed applications for the analysis of biomedical images. Such applications involve a set of operations that go from improvement of images to production of results that allow users to diagnose. Using SIMA it is possible to exploit, in an integral way, the available resources in a heterogeneous computer network for image processing . This tool has been developed in JAVA and no previous knowledge in distributed programming is required for its proper use it. A graphic interface allows the definition of applications for image processing. A distributed application is constructed by composition of operations, starting from a set of default basic operations (segmentation, filters, calculation of areas).