INTRODUCTION: The aim of this study was to determine the effect of hNT neuron transplants on motor neuron function in SOD1 (G93A) mice when motor deficits were already apparent. METHOD: The hNT neurons were implanted into L 4 -L 5 segments of the ventral horn spinal cord of mice at 15-16 weeks of age: either G93A mice, transgenic mice carrying the normal allele for human SOD1 gene (hTg), or control wild type mice (wt). Behavioral tests (rotorod, beam balance, extension reflex, footprint) were performed prior to transplantation and at weekly intervals afterwards. RESULTS: HNT neuron transplantation in the SOD1 mice delayed disease progression for 3-4 weeks, although lifespan was not affected. CONCLUSION: These results suggest that hNT neuron transplantation may be a promising therapeutic strategy for ALS in the later phase of the neurodegeneration.