Objective: To study hTERT mRNA expression in ameloblastoma (AB) and its correlation with cyclin A, p53 protein and proliferation cell nuclear antigen (PCNA) and to investigate clinical biological significance. Methods: Expression of cyclin A and p53 protein in AB and expression of PCNA and hTERT mRNA was detected by Sp method and in-situ hybridization. Results: The positive ratios of hTERT mRNA, cyclin A , p53 protein and PCNA were 94.4% (51/54), 66.7% (40/60), 85.7% (42/49) and 78.1% (25/32), respectively. Strong correlations were found between hTERT mRNA and cyclin A, p53 protein and PCNA (r_s = 0.914, 0.848, 0.804, P < 0.05). Conclusions: Telemerase activity has correlations with the accumulation of p53 protein and cell proliferation and differentiation. It is regulated by cyclin A and has a higher expression in phase S.