The paper describes a platform developed for the secure management and analysis of medical data and images in a grid environment. Designed for telemedicine and built upon the EGEE gLite middleware and particularly the metadata catalogue AMGA as well as the GridSphere web portal, the platform provides to healthcare professionals the capacity to upload and query medical information stored over distributed servers. A job submission environment is also available for data analysis. Security features include authentication and authorization by grid certificates, anonymization of medical data and image encryption. The platform is currently deployed on several sites in Europe and Asia and is being customized for applications in the field of telemedicine and medical physics.