Circulating endothelial cells (CECs) are increased in sickle cell disease, myocardial infarction, and acute lung injury. The purpose of this study was to determine whether CECs are a prognosticating marker for the development of pneumonia in burn patients with/without inhalation injury in addition to their relationship to proinflammatory cytokines. There were 24 patients: 6 with inhalation injury, 5 with burn only,and 13 with burn plus inhalation injury. CECs were measured by anchored cytometry (Clarient ChromaVision, San Juan Capistrano, CA). In addition, plasma levels of tumor necrosis factor-α, interferon-γ, and interleukins (IL)-10, IL-6, IL-4, and IL-2 were compared with CEC levels. Patients with inhalation injury had a significant (P < .001) paucity of CECs compared with the thermally injured with inhalation. There was a statistically significant increase in inteferon-γ, tumor necrosis factor-α, and IL-6, IL-4, and IL-2 compared with control patients (P < .01), with a concomitant increase in the number of CECs. The numbers of CEC levels did not prognosticate which patients would develop pneumonia. Burn patients with/without inhalation injury had concurrent increase in CECs and proinflammatory cytokines during the acute phase of injury.