Raynaud's phenomenon is a frequent asphyxial vascular syndrome interesting the 4% of general population. In most of cases it is a functional problem (Raynaud's disease). Less frequently it has an organic cause (Raynaud's syndrome). The pathogenesis of primitive Raynaud's phenomenon remains an enigma. In secondary Raynaud phenomenon the attacks of vasospasm can be explained by the physiopathologic events characterizing the underlying disease. For example, multiple cytokines, transforming grow factor beta, serum immunocomplexes are of great importance in the contest of connective diseases. Clinical examination, some usual laboratory and roentgenographic investigations and nailfold capillary microscopy are of particular importance in orientating the diagnosis.