An essential prerequisite for progress in understanding the pathophysiology and the clinical treatment of rare diseases is the national cooperation of specialized centers. The German network for systemic sclerosis (DNSS) is such an interdisciplinary union of hospitals and research centers with a special interest in systemic sclerosis (SSc). A core activity is the patient register of the DNSS which includes over 3,100 patients. It is one of largest national registers of SSc patients worldwide and comprises prospective data on diagnostics as well as primarily therapy of the patients. The register has now proven to be an extremely successful basis for clinical research and basic studies within the framework of international cooperation. The most important results of the cooperation and the register will be presented in this article.