Objective: To study the expression of connexin43 (Cx43) gene and its correlation with the apoptosis related genes Bcl-2 and Bax in transitional cell carcinoma of the bladder (BTCC), and to investigate the role of Cx43 in the BTCC. Methods: Reverse transcription polymerase chain reaction was used to detect the expression of Cx43 mRNA and immunocytochemistry technique was used to detect the expressions of Bcl-2 and Bax proteins in 60 cases of BTCC tissues, and compared with that of 15 cases of pericancerous tissues and 15 cases of normal bladder tissues. Results: The positive expression rate of Cx43 mRNA in 60 cases of BTCC tissues was 43.33% which was significantly lower than that in pericancerous tissues (73.33%) and normal tissues (100%) (χ2 = 17.58, P < 0.01). The expression of Cx43 had significant negative correlation with the pathological degree and lymph node metastasis of BTCC (χ2 = 9.33 and 9.74, respectively, P < 0.01). However, no correlation was found between the expression and patient sex, age, clinical staging and diameter and growth pattern of BTCC (P > 0.05). Expression of Cx43 negatively correlated with Bcl-2 protein (r = -0.63, P < 0.01) and positively correlated with Bax protein (r = 0.52, P < 0.01). Conclusion: The down-regulated expression of Cx43 gene was closely associated with the development, invasion and metastasis of BTCC. It could be used as a prognostic indicator for BTCC. Cx43 gene may have antagonistic effects with Bcl-2 gene and synergic with Bax gene in the initiation and progression of BTCC. Objective: To study the expression of connexin43 (Cx43) gene and its correlation with the apoptosis related genes Bcl-2 and Bax in transitional cell carcinoma of the bladder (BTCC), and to investigate the role of Cx43 in the BTCC. Methods: Reverse transcription polymerase chain reaction was used to detect the expression of Cx43 mRNA and immunocytochemistry was used to detect the expressions of Bcl-2 and Bax proteins in 60 cases of BTCC tissues, and compared with that of 15 cases of pericancerous tissues and 15 cases of normal bladder tissues. Results: The positive expression rate of Cx43 mRNA in 60 cases of BTCC tissues was 43.33% which was significantly lower than that in pericancerous tissues (73.33%) and normal tissues (100%) (χ2 = 17.58, P <0.01 ), The expression of Cx43 had significant negative correlation with the pathological degree and lymph node metastasis of BTCC (χ2 = 9.33 and 9.74, respectively, P <0.01). However, no correlation was found between the expression Expression of Cx43 was negatively correlated with Bcl-2 protein (r = -0.63, P <0.01) and positively correlated with Bax protein (r = 0.52, P <0.01). Conclusion: The down-regulated expression of Cx43 gene was closely associated with the development, invasion and metastasis of BTCC. It could be used as a prognostic indicator for BTCC. Cx43 gene may have antagonistic effects with Bcl- 2 gene and synergic with Bax gene in the initiation and progression of BTCC.