Objective：To investigate the change in myogenin expression at different time in long-term denervated human posterior cricoarytenoid muscles（PCAMs）, so as to provide a theoretical basis for timing of reinnervation. Methods: Thirty-eight specimens of denervated human PCAMs were divided into 4 groups according to the period of denervation: 6-12 months denervation group（n=12） , 1-2 years denervation group（n=10）, 2-3 years denervation group（n=8）, and over 3 years denervation group（n=8）. Another 12 specimens of normal PCAMs served as control. The patients in all groups were age- and sex-matched. The expression of myogenin protein and mRNA was studied using immunofluorescence staining and real-time PCR analysis, respectively. Results: Immunofluorescence staining showed that the positive myogenin expression was mainly found in the myonuclei of PCAMs with a denervation period less than 3 years; no positive staining was found in the myonuclei of control group. The expression of myogenin in myonuclei and the ratio of positive cells were up-regulated in the 6-12 month denervation group compared with those in the control group; the expression and the ratio peaked in 1-2 years denervation group and decreased again in the 2-3 years denervation group, but was still significantly higher than those of the control group (all P<0.01). There was hardly any expression of myogenin 3 years after denervation. Results of RT-PCR showed no myogenin mRNA expression in the control group; the expression in 1-2 years, 2-3 years, and more than 3 years denervation groups were 4 times, 64 times, and half that of the 6-12 months denervation group, respectively (all P<0.05). Conclusion: It is indicated that there is a potential for muscle regeneration within 3 years of denervation.