[Abstract] Objective: To investigate the expression of galectin-3 in bladder cancer tissues and its correlation with clinicopathological characteristics of bladder cancer patients, as well as to explore its effect on the proliferation, invasion and apoptosis of bladder cancer T24 cells. Methods:Atotal of 104 cases of pathologically confirmed bladder cancer tissues and the corresponding adjacent tissues were collected from the patients treated at the Affiliated Hospital of North Sichuan Medical College from May 2014 to June 2016. Immunohistochemistry staining was used to determine the galectin-3 protein expression in both cancer and adjacent tissues, and the correlations between galectin-3 expression and clinical pathological features were analyzed. siRNA-Gal3 and siRNA-Control were transfected into T24 cell, respectively. The expression of galectin-3 protein was detected by Western blotting, the proliferation of cells was detected by MTT assay; the invasion of cells was detected by Transwell assay; and the cell apoptosis was determined by Flow cytometry. Results: The positive rate of galectin-3 in bladder cancer tissues was significantly higher than that in adjacent tissues (73.1% vs 9.6%, P<0.05). The expression of galectin-3 in bladder cancer was correlated with histological grade, depth of invasion, lymph node metastasis and TNM stage (all P <0.05), but not with sex and age (P>0.05). The expression of galectin-3 was down-regulated significantly by siRNAGal3 (P<0.05). After interference with galectin-3, the proliferation and invasion of T24 cells was significantly decreased (all P<0.05) but the apoptosis was significantly increased (P<0.05). Conclusion: Galectin-3 is over-expressed in bladder cancer and is closely related to the clinicopathological features of bladder cancer patients. Interference of galectin-3 protein expression can inhibit proliferation and invasion and promote cell apoptosis of bladder cancer T24 cells. ··