To explore the effect of 2,5-hexanedione on permeability of blood-nerve barrier, adult Wistar rats were administered with 400 mg x kg(-1) x d(- 1) 2,5-hexanedione to establish animal model of 2,5-hexnedione neuropathy. Evans blue was injected through left femoral vein of the rats after the model had been established. The distribution of fluorescence in sciatic-tibial nerve was observed and assessed. For the transverse sections of sciatic-tibial nerves, the average fluorescence intensity of proximal section was stronger (p < .01) than those of intermediate and distal sections and the average fluorescence intensity of intermediate section was stronger (p < .01) than that of distal section in the intoxicated group. In the control, the weak fluorescence was shown, and average fluorescence intensity of distal section was stronger (p < .05) than that of proximal section. The average fluorescence intensity of proximal, intermediate and distal sections in the intoxicated group was stronger (p < .01) than those of the corresponding sections in the control. For the longitudinal sections of sciatic-tibial nerves, fluorescence was observed in both proximal and distal sections in the intoxicated group. The fluorescence intensity of distal section in the control was weak and almost no fluorescence was shown in the proximal section. The permeability of blood-nerve barrier could be increased by 2,5-hexanedione.