In the present study the effect of the administration of GH and T3 on glucose distribution in the regenerating nerve was studied. The right sciatic nerve of 40 male rabbits was crushed at a specific site so that axonotmesis ensued. The animals were divided into two equal groups: one for the study of the effects of human growth hormone (hGH) and the other of triiodothyronine (T3). In all animals 14C-D-glucose a([14C]D-G) was injected iv as a tracer. The sciatic nerves from both sides were removed from all animals, divided into four equal segments and checked for radioactivity. In all cases an increased concentration of [14C]D-G appeared in the crushed nerve as compared with the intact one. GH administration caused a decrease in [14C]D-G uptake in both intact and injured nerves. T3 administration caused a significant decrease in [14C]D-G levels in the blood but did not substantially change [14C]D-G uptake in the crushed nerves as a whole. T3 administration appeared also to cause a peripheral displacement of the site of maximum [14C]D-G concentration in the injured nerve, indicating possibly an increased regeneration rate.