Acute respiratory distress syndrome (ARDS) is a common and severe disease process seen in critically ill patients. ARDS can be separated into those patients who have primary or secondary ARDS. The mechanisms of disease and its outcome can be quite different between these two processes. Relevant to this issue, the data of Nakae et al. reported in this issue are interesting. These investigators extended their previous work by examining the systemic expression lung injury by measuring serum levels of a specific lung protein, surfactant apoprotein D, as well as a marker of leukocyte activation, neutrophil elastase, in the blood of septic patients with or without ARDS. Their data clearly show that both markers are elevated in ARDS patients and the more elevated these levels the greater likelihood of death. We can conclude from these data that lung-specific makers of injury are preferentially elevated in ARDS patients with sepsis.