Objective：To investigate the relationship between p38 mitogen-activated protein kinase (p38MAPK), nuclear factor-κB (NF-κB) and cyclooxygenase-2 (COX-2), so as to study the roles of p38MAPK, NF-κB and COX-2 in diabetic nephropathy. Methods: Rat mesangial cell line HBZY-1 was incubated with certain concentrations of glucose(25 mmol/L), insulin(100 mmol/L), H2O2(100 mmol/L) and glycation endproducts (AGEs)(100 mg/L) with or without pretreatment with SB203580, a specific inhibitor of p38MAPK, then the expression of p38MAPK, NF-κB and COX-2 in the HBZY-1 cells was examined. Results: High glucose, high insulin, H2O2 and AGEs independently activated p38MAPK, increased p38MAPK phosphorylation, and significantly up-regulated the expression of NF-κB and COX-2 compared with the control group (P<0.01). Pretreatment with SB203580 significantly decreased expression of NF-κB and COX-2 compared with the corresponding stimulating group (P<0.01). Conclusion: p38MAPK may induce renal damage during diabetic nephropathy by activating NF-κB and COX-2, indicating that p38MAPK, NF-κB and COX-2 may play important roles in the development of diabetic nephropathy.