A modification is proposed for the Bielschowsky-Gross' method to be used in paraffin cuts for the neurofibrils and the peripheral nerve endings. The method is easy to perform and can be accomplished in a few hours, what cannot be said of most of impregnation methods for paraffin cuts. The fixation is performed with a 2% formalin solution neutralized with magnesium carbonate, either or not combined with 1% Somniphene solution; the use of Somniphene affords a more vigorous impregnation of the fibers and avoids, up to the maximum, the impregnation of conjunctive fibers. The mordansage is made up with a recent 10% silver nitrate solution, a prolonged fixation (about one hour) being advisable for the coloration of the fundamental sympathetic plexus. The impregnation is made up with ammoniacal silver oxide solution prepared after Bielschowsky's recommendations (addition of ammonia to a 10% silver nitrate solution until complete dissolution of precipitate), which can be substituted by the solutions proposed by Rio-Hortega. Arteta and Jabonero. Toning (gold turn-over) is performed with the solution recommended by Castro (one drop of acetic acid for every 10 ml of 1/600 yellow gold chloride solution). The results were satisfactory, a perfect impregnation of neurons of the Gasser ganglion being achieved; in preparations with Somniphene the nervous fibers and the cell processes appeared perfectly impregnated and the preparations showed an absolute cleanliness. In the coecal appendix the nerve endings were also perfectly impregnated, contrasting with muscular and conjunctive elements, specially when Somniphene was employed. The fundamental sympathetic plexus, Stohr's terminal reticulum and the thin sympathetic endings showed close relations to the interstitial cells, with good synaptic pictures. With this proposed method it is possible to impregnate, in 4 to 5 hours, about 30-40 cuts and this can be considered an excellent work profit.