This study investigated the effect of buyang huanwu decoction on the regeneration of a 10-mm gap of rat sciatic nerve created between the proximal and distal nerve stumps, which were sutured into silicone rubber tubes. Empty silicone rubber tubes with no further treatment were used as controls. Six weeks after implantation, 89% of the animals orally administered the buyang huanwu decoction exhibited regeneration across the nerve gaps, whereas only 70% had regenerated in the control group. Both qualitative and quantitative histology of the regenerated nerves revealed a more mature ultrastructural organization with significantly higher numbers of myelinated axons, larger endoneurial areas, higher axon densities and a larger percentage of axon area per total nerve area in the buyang huanwu group than in the controls. These results showed that the buyang huanwu decoction had a growth-promoting effect on the regenerated nerves.