TNFα is a cytokine of innate immunity. The principal cellular targets and biologic effects include activation of endothelial cells, neutrophil activation, fever, liver synthesis of acute phase proteins, muscle and fat catabolism, and apoptosis of many cell types. In our study, we found highly increased TNFα levels in the nvA(H1N1)mild disease, nvA(H1N1)-ARDS and bacterial ARDS groups compared to the control group. TNFα is significantly higher in nvA(H1N1)-ARDS versus nvA(H1N1)mild disease, with similar results being found by To and colleagues and Bermejo-Martin and colleagues [8, 9] . This cytokine is also significantly increased in bacterial-ARDS versus nvA(H1N1)-ARDS.