[Abstract]Objective: To investigate and significance the expression of 5-LOX(5-lipoxygenase), NF-kB P65( Nuclear factor kappa B P65 )in colon mucosa of ulcerative colitis(UC)and to analyze their correlation．Methods: The biopsies from 32 UC patients and 26 healthy controls were collected，and the expression of 5-LOX, NF-kB P65 mRNA and protein in colonic mucosa was determined by Real-time fluorescent quantitative reverse transcription polymerase chain reaction(RT-PCR) and immunohistochemistry assay respectively．The patients were graded according to endoscopic and histological grading．Results: The expressions of 5-LOX, NF-kB P65 mRNA and protein in UC patients were significantly increased than those in healthy controls, which wag correlated with histological grading. A good positive correlation was found between 5-LOX and NF-kB P65.Conclusion: The expression of 5-LOX is closely related to NF-kB P65 in colon mucosa from UC patients. They may play a pivotal role in inflammation of UC.