To Study cellular characteristics of human cementoblasts using a cellular model is important for understanding the mechanisms of homeostasis and regeneration of periodontal tissues. However, at present no immortalized human cementoblast cell line has been established due to limitation of the life span. In the present study, therefore, we attempted to establish human cementoblast-like cell lines by transfection with telomerase catalytic subunit hTERT gene. Two stable clones (HCEM-1 and -2) with high telomerase activity were obtained and they grew over 200 population doublings without significant growth retardation. The expression of mRNA for differentiation markers, type I collagen, alkaline phosphatase (ALP), runt related transcription factor 2, osteocalcin and bone sialoprotein was revealed in these clones by RT-PCR. Moreover, these cells showed high ALP activity and calcified nodule formation in vitro. Interestingly, HCEM-2 showed cementum like formation on the surface of hydroxyapatites granules by subcutaneous transplantation into immunodeficient mice with hydroxyapatite granules. Thus, we established human cementblast-like cell lines with high mineralization activity. We suggest that HCEM cell lines can be useful cell models for investigating the characteristics of human cementoblasts.