Abstract: Abstract　Objective: To investigate the expression and clinical significance of cyclin G1 and cyclin G2 in human esophageal squamous cell carcinoma ( ESCC ). Methods: A total of 60 paraffin-blocked ESCC specimens filed in the Department of Pathology, The First Affiliated Hospital of Bengbu Medical College, Bengbu, China from 2007 to 2008 were enrolled in our study, in which 20 cases were normal esophageal mucosa. All the enrolled cases have complete clinical and pathologic data. Immunohistochemical Elivision staining was used to assay cyclin G1 and cyclin G2 expression in the aforementioned tissues. Results: The cyclin G1 was positive in 61.7% of the ESCC cases, which is apparently higher than that in normal esophageal mucosa ( 25.0%; P < 0.05 ). In addition, the positive rate of cyclin G2 was significantly lower in ESCC ( 66.7% ) than in the normal esophageal mucosa ( 90.0 % ) ( P < 0.05 ). In ESCC, cyclin G1 expression is negatively correlated with that of cyclin G2 ( P < 0.05 ). Conclusion: With the increase in cyclin G1 expression in esophageal squamous cells, the expression of cyclin G2 protein decreases, which suggests a mutual negative feedback mechanism between cyclin G1 and G2. Both proteins play an important role in the occurrence and progression of ESCC.