Background: This study examined whether there is any difference in the lung cytokine and cytokeratin 19 levels between young and middle-aged mice after bone fracture and soft-tissue trauma hemorrhage (Fx-TH). Methods: Young (6-8 weeks) and middle-aged (12 months) C3H/HeN male mice were subjected to right lower leg fracture, trauma hemorrhage (mean arterial blood pressure to 35 ± 5 mm Hg for 90 minutes), and resuscitation. Results: The tumor necrosis factor α level in the lung increased significantly at 2 hours after Fx-TH in both young and middle-aged mice, whereas at 24 hours the levels remained significantly higher in middle-aged mice. Interleukin-6 levels increased significantly 24 hours after Fx-TH in both groups, whereas interleukin-10 levels increased only in middle-aged mice at 24 hours under those conditions. Monocyte chemoattractant protein-1 levels increased significantly 2 hours after Fx-TH. The protein and messenger RNA levels of cytokeratin 19 were significantly higher in middle-aged mice compared with young mice after Fx-TH. Conclusion: These results suggest that age influences the lung inflammatory response after Fx-TH. © 2007 Excerpta Medica Inc. All rights reserved.