The aim of the project is to establish a Swiss cohort of patients with Systemic lupus erythemaosus (SLE) providing clinical data and biological samples for research on the pathogenesis, diagnostic procedures and treatment of SLE. The proposed structure of SSCS aims to reflect the particular interdisciplinary character of the disease as well as the federal structure of the health system. All patients with definitive or probable SLE according to the criteria of the American College of Rheumatology (ACR) will be included upon informed consent. Collected data consist of an essential dataset containing basic data on current and former disease manifestations, an extended dataset on disease activity and biological parameters, supplementary datasets on diagnostic procedures and treatment, and a quality-of-life questionnaire. Patient data is anonymised and then transferred to a central database. Serum, plasma, peripheral blood mononuclear cells (PBMC) and genomic nucleic acids are collected and stored at the recruiting centres until a central biobank will be established. Collection of follow-up data and blood samples will take place routinely every twelve months or earlier in case of flares. A cohort of well characterised SLE patients is likely to become an important investigational and long-term tool for clinical as well as experimental research on mechanisms of disease, disease manifestations, clinical outcomes and new therapeutic approaches. All Swiss medical institutions taking care of SLE patients are invited to participate. SSCS will serve as an interdisciplinary network between experimental and clinically oriented scientists, between different departments, between university and non-university hospitals, and between hospitals and practitioners. Existing or evolving scientific questions on SLE and on systemic autoimmunity in general may be addressed by separate research projects using SSCS’ resources.