Thirty two fire victims with smoke inhalation, with or without burns, and 26 control subjects had bronchoalveolar lavage performed. Cell yields and differential cell counts were assessed. All patients and controls were cigarette smokers. Patients with smoke inhalation (SI) injury generally showed higher total bronchoalveolar lavage (BAL) cell yields, and this was significant on repeat lavage from 12 patients. The increase was almost entirely due to an increase in the proportion of neutrophils in patients with smoke inhalation alone (S) and those with cutaneous burns as well as smoke inhalation (S + B). On sequential lavage of 12 patients with smoke inhalation (SI) the proportion of neutrophils had increased; this was significantly higher than on initial lavage. Using various macrophage markers, the proportions of macrophage subgroups were determined. There was an increase in UCHM1 and RFD9 positive cells in each subgroup: the increase in UCHM1 positive cells was significant in patients with burns as well as smoke inhalation, and the increase in RFD9 positive cells was significant in patients with smoke inhalation alone. Assessment of the role of such cells in the development of acute lung injury (such as adult respiratory distress syndrome) may be important in our understanding of the mechanisms entailed.