Objective To investigate expression of slug and E-cadherin in pancreatic cancer tissues and determine the inhibitory effects of anti-Slug, an anti-sense plasmid, on the invasion of pancreatic cancer cell lines in vitro. Methods Slug and E-cadherin protein and mRNA was analyzed by IHP and RT-PCR in 36 cases of pancreatic cancer. Then anti-Slug plasmid was transfected into herin and Slug expression. The inhibitory effects of anti-sense Slug were also detected by Transwell motility assay and Matrigel invasion assay. Results The expression of Slug and mRNA in metastatic pancreatic cancer tissue was higher than that in non-metastatic tissue. E-cadherin and mRNA was lower in metastasis tissues(P＜0.05). The inverse relationships were further observed by transient transfection of anti-Slug into SW1990H4 cells. The downregulated expression of Slug and re-expression of E-cadherin were found. The Slug mRNA levels were 0.985±0.016,0.973±0.014, 0. 554±0. 011 after 0, 48 h of transfection of anti-sense Slug, and that of E-cadherin were 0.120±0.001, 0.360±0.002, 0. 727±0. 006, respectively. The diference was significant between different time points (P＜0.05). The Slug mRNA levels were 0. 206±0.017, 0.968±0.015, and that of E-cadherin were 0. 18±0.002,0.727±0.006 after stable transfection of anti-sense Slug, and control plasmid, respectively. The diference was significant (P＜0.05). The motility activity(393±28, 352±24, 96 ±13 )and the invasion activity (223 ± 69, 202 ± 64, 65 ±19) of1 antisense Slug transfectant cells were significantly decreased as compared with those of control cells (P＜0.05). Conclusions Higher expression of slug and lower expression of E-cadherin is related to the invasion and metastasis in pancreatic cancer. A reverse corelation of E-cadherin and Slug expression exists in pancreatic cancer. Slug is possibly a potential target for cancer gene therapy blocking invasion and metastasis in human pancreatic cancer.