An 81-year-old man was admitted after developing chest pain during a meal. Oesophagoscopy revealed an impacted bolus of chicken meat which could not be removed and his left hemithorax became contaminated following perforation. He underwent oesophageal decompression with a gastric sump drain, a retrograde gastro-esophageal tube and feeding jejunostomy. Prior to surgery he met the oxygenation criteria for acute respiratory distress syndrome (ARDS) and following surgery he was intubated and his lungs ventilated, requiring oxygen 100% and an ARDS ÔprotectiveÕ ventilatory strategy. His static compliance was 22 ml. cm H2O) 1 (normal value> 50 ml. cm H2O) 1) and his resistance was 11.4 cm H2O. ml) 1. He was commenced on salbutamol nebulisers, ciprofloxacin, clindamycin and fluconazole; Streptococcus viridans was grown from blood cultures. On the second day a trial of the nebulised mucolytic agent dornase alfa (Roche UK, Welwyn Garden City, UK), at a dose of 2.5 mg every 6 h was started. Over the next 36 h his tracheal suction products became copious with mucus plugs and his oxygen requirements reduced to 50%, resulting in aPaO2 of 12.4 kPa. His static compliance improved progressively over the next 72 h to 59 ml. cm H2O) 1. Weaning was progressive and he was extubated on day 8. Dornase alfa, a recombinant engineered enzyme, is a mucolytic allowing the degradation of extracellular DNA with improved expectoration and clearance of mucus. Its use is well described in the management of cystic fibrosis where it allows improved clearance and possibly modulates the inflammatory airway process [1, 2]. In the UK the National Institute for Clinical Excellence (NICE) has recently considered the agent for use in acute exacerbations of chronic obstructive pulmonary disease [3] and case reports exist of benefit in acute life threatening asthma [4]. ARDS is regionally heterogeneous and up to one third of dependent alveolar air spaces may be replaced by fluid and cellular debris [5], producing de-recruitment and increased shunt fraction. Recruitment of obstructed alveolar units would be a mechanical benefit in ARDS; such a strategy could reduce barotrauma and promote homogeneous ventilation. Similarly, opening previously closed dorsal units would reduce the shunt fraction, allowing improvement in oxygenation and reduced oxygen requirements. Furthermore, the removal of inflammatory exudates may have a protective effect on the lungs and the organism generally if it can reduce the production of inflammatory mediators [2]. Salbutamol is commonly administered due to its beta2 adrenoceptor mediated bronchodilation and, particularly in ARDS, the stimulation of alveolar Na⁄ K ATPase may aid mobilization of alveolar fluid to the interstitium and maintain intercellular tight junction integrity [6]. While inhaled nitric oxide is a well recognised therapy in ARDS, delivery is complex and expensive, and its use is not associated with reduced mortality. The use of nebulised dornase alfa in ARDS and acute lung injury is unexplored and intuitively reasonable. There is little suggestion of harm and delivery is straightforward. Its use should be evaluated in larger prospective studies.