Abstract: Objective To determine the expressions of Cdtl and Oeminin genes in human embryonic lung fibroblasts(HEL) and the influence of human cytomegalovirus(HCMV)infection.Methods The HEL cells were synchronized in G0/G1 by serum starvation.Cell cycle of HEL cells was detected by flow cytometry.Synchronized HEL cells were infected with HCMV,at the same time the mock-infected group was set as control.Infected HEL cells were harvested at 12 h,24 h,48 h,72 h and 96 h post infection.The expressions of Cdtl and Geminin genes were detected with semi.quantitative RT-PCR. Results 82.8% of the HEL cells were in G0/G1 phase after serum starvation.Analysis showed that the expressions of Cdtl gene in HCMV-infected group were statistically lower(all P=0.000) than those in the mock-infected group at 12 h and 24 h post infection,but higher than the latter group at 48 h and 72 h post irrfection.The expressions of Geminin mRNA in HCMV-infected group were statistically higher than those of the mock-infected group at 12 h and 24 h post infection,but lower than tha latter group at 48 h and 72 h post infection(all P=0.000). Conclusions Serum starvation is a better method to synchronize the HEL cell.HCMV can induce abnormal expressions of Cdtl and Geminin genes and Geminin/Cdtl imbalance.which may play a role in HCMV blocked cell cycle in G1 phase.