Ross syndrome is characterized by tonic pupil, areflexia and anhidrosis and the underlying lesion affects postganglionic skin sympathetic nerve fibers. We describe a 51 years-old man complaining of anhidrosis since adolescence when this problem was limited to the lower arms. The thermoregulatory sweating test disclosed generalized anhidrosis (GA) except for two small skin areas located in the right palm and left neck. Immunofluorescence analysis disclosed no cholinergic sudomotor fibers around the sweat glands of non sweating skin areas which were evident although sparse and deranged in the sweating site. In our patient GA was induced by a postganglionic sympathetic skin nerve fibers degeneration as found in the Ross syndrome although his clinical picture was incomplete lacking tonic pupil and areflexia. Isolated generalized anhidrosis (GA) induced by a postganglionic sympathetic nerve fibers degeneration directly evaluated by skin biopsy has not been previously described.