Histological aspects of nervous regeneration after section of peripheral nerves by different surgical procedures were studied aiming the prevention of the amputation neuroma. The material (sciatic nerves of 72 guinea pigs) was divided into 12 groups according to the surgical technique used. The pieces were fixed with 20% formol solution neutralized by magnesium carbonate and impregnated by Boeke's method with gold turn-over according to Castro's method or fixed with ammoniacal alcohol and impregnated by Cajal's reduced silver nitrate. The different surgical methods employed have determined variations in the development of degenerative and proliferative alterations, which were classified in four grades : in grade I predominates the degenerative alterations being the proliferative ones represented by a slight increase in the number of neurofibrillae not intercrossed; in grade II the proliferative alterations are more striking and there is intercrossing of the neurofibrillae; in grade III the proliferative alterations predominate and there is an increase of intercrossing fibrillae at the boutons terminaux; in grade IV the proliferative alterations dominate the histological picture (fibrillar dicotomization, argentophile granules at the end of the fibrillae, marked intercrossing). Grade I reaction was considered as absence of neuroma. With surgical methods that offer better protection to the bisected nerve the incidence of neuroma is smaller since the procedures for this protection determine a hyperplasia of the connective tissue; the resulting scar hinders the proliferation of fibrillae and the influence of neurotropic substances elaborated by Schwann cells and by the neighbouring tissues.