【Abstract】Objective To explore Toll-like receptor 4 (TLR4) expression and distribution in rat pancreas.Methods Reverse transcriptase-polymerase chain reaction (RTPCR) and immunohistochemistry (IHC) were applied to detect expression of TLR4-mRNA and TLR4 protein respectively. Results RT-PCR of RNA isolated from rat pancreatic tissue yielded the predicted amplicon for the TLR4. IHC/immunofluorescence revealed TLR4 protein mainly distributed in the epithelium of the pancreatic duct, vascular endothelium of the exocrine section, endocrine islet also had some signs of distribution. No TLR4 protein signal could be detected in the acinar cells. Conclusion TLR4 could be detected in rat pancreas. Its distribution is consistent with its roles in immune surveillance, mainly in tissues exposed to the external environment such as pancreatic duct as well as in immunologically important settings such as pancreatic vascular endothelium. Islet also has some signs of distribution. No TLR4 expression in acinar cells, suggesting TLR4 immunological involvement in the pathophysiology of pancreas.