OBJECTIVETo determine whether the administration of lisofylline (1-5R-hydroxyhexyl-3,7-dimethylxanthine) would decrease mortality in patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). DESIGNA prospective, randomized, double-blind, placebo-controlled, multicenter study. SETTINGIntensive care units at 21 hospitals at the ten centers constituting the ARDS Clinical Trials Network. PATIENTSA total of 235 patients who met eligibility criteria were enrolled in the study (116 into the lisofylline group, 119 into the placebo group). INTERVENTIONSPatients were randomized to receive either lisofylline or placebo. The dose of lisofylline was 3 mg/kg with a maximum dose of 300 mg intravenously every 6 hrs. The intravenous solution of study drug was administered over 10 mins every 6 hrs. Dosing was continued for 20 days or until the patient achieved 48 hrs of unassisted breathing. MEASUREMENTS AND MAIN RESULTSThe trial was stopped by the Data Safety Monitoring Board for futility at the first scheduled interim analysis. The patient groups had similar characteristics at enrollment. No significant safety concerns were associated with lisofylline therapy. There was no significant difference between groups in the number of patients who had died at 28 days (31.9% lisofylline vs. 24.7% placebo, p = .215). There was no significant difference between the lisofylline and placebo groups in terms of resolution of organ failures, ventilator-free days, infection-related deaths, or development of serious infection during the 28-day study period. The median number of organ failure–free days for the five nonpulmonary organ failures examined (cardiovascular, central nervous system, coagulation, hepatic, and renal) was not different between the lisofylline and placebo groups. Although lisofylline has been reported to decrease circulating free fatty acid levels, we did not find any such treatment effect compared with placebo. CONCLUSIONSIn this study, there was no evidence that lisofylline had beneficial effects in the treatment of established ALI/ARDS.