Abstract: Objective To study the biological characteristic of the cultured ligament cells derived from patients with ossification of posterior longitudinal ligament of the spine(OPLL).Methods The ligamental tissue of the spine was separated from OPLL patients and non OPLL patients.Eight ossified cell lines(OL1-OL8)and seven non ossified cell lines(NL1-NL7)were built.The pheno type of all the cell lines were observed.Results Four of eight OL cell lines expressed osteoblast pheno type with high alkaline phosphatase(ALP)activity(1.05±0.43/mL).The forming of bony tubercle,secretion of gly cosaminoglycans,calcium deposit were observed and osteocalcinl(OC)was detected(OL 1:3.7 ng/mL,OL 3:3.5 ng/mL,OL 7:2.9 ng/mL,OL 8:2.6 ng/mL).How ever,all NL cell lines expressed fibroblast pheno type with low ALP activity(0.47±0.05/mL)and no bone tubercle formation and OC secretion.Conclusion Spinal ligament cell line was established successfully.Cultured ligament cells from OPLL patients can express osteobla stpheno type in vitro.