The aim of the study was to evaluate morphologic alterations of microvessels quantitatively and objectively in patients with various connective tissue diseases (CTD) by means of histomorphometry. Standardized histomorphometrical examination of dermal microvessels was performed by means of interactive semi-automated image analysis in specimens obtained by the technique of capillaroscopically guided nailfold biopsy in 31 patients with various CTD and 8 controls without CTD. Histomorphometry revealed a significant enlargement, an increased dysmorphia and a diminished number of microvessels as well as an increased papillary area in CTD-patients compared to controls. The most severe alterations of microvessels were seen in scleroderma and MCTD, whereas in SLE the morphometrically observed changes were less impressive. By means of histomorphometry morphological changes of the microvasculature can be analyzed quantitatively and objectively. Since differences regarding nature and extent of the microvascular injury between particular conditions can be disclosed by the technique, this approach may be a useful tool to identify distinct patterns of microangiopathy in the various types of CTD.