The authors relate the data on vegetative sweating fibers studied by the method of evoked skin sympathetic potentials in patients with diabetes mellitus, Charcot-Marie atrophy, spinal amyotrophy, Guillain-Barre syndrome, essential hyperhidrosis, and in those with Raynaud's phenomenon and thyrotoxicosis. A remarkable decrease of conduction by sweating fibers was revealed in patients with diabetes mellitus, Charcot-Marie atrophy and Raynaud's phenomenon; a moderate decrease was shown by the patients with Guillain-Barre syndrome and by those with spinal amyotrophy. The conclusion is made about the high information content of the method.