Capillaroscopy has high diagnostic and prognostic value in autoimmune connective tissue diseases, in particular systemic sclerosis (SSc). Our working group has developed a consensus on nomenclature, technical equipment, procedure, and diagnostic interpretation of results. The following are required: binocular microscopes with at least 20-/50- and 160-/200-fold magnification and digital archiving. Documentation of defined findings is mandatory. The simultaneous occurrence of, e.g. caliber variations, ectasia, ramifications, elongation (length > 350 microm), torsion (at least two crossing segments per capillary loop), sludge, hemorrhage, and edema is of pathological significance. The isolated occurrence of bushy capillaries (multiple ramifications), thrombosis, giant capillary (capillary lumen > 50 microm), and avascular areas also indicates disease. The latter two findings are highly specific for SSc. Other findings are consistent with connective tissue diseases. These standardized definitions increase quality and comparability of nailfold capillaroscopy in Germany.