Introduction. We investigated the effects on hemodynamics and gas exchange of a lipid emulsion enriched with omega-3 fatty acids in patients with ARDS. Methods. The design was a prospective, randomized, double-blind, parallel group study in our Intensive Medicine Department of Vall d'Hebron University Hospital (Barcelona-Spain). We studied 16 consecutive patients with ARDS and intolerance to enteral nutrition (14 men and 2 women; mean age: 58 ± 13 years; APACHE II score: 17.8 ± 2.3; Lung Injury Score: 3.1 ± 0.5; baseline PaO2/FiO2ratio: 149 ± 40). Patients were randomized into 2 groups: Group A (n = 8) received the study emulsion Lipoplus ® 20%, B.Braun Medical (50% MCT, 40% LCT, 10% ω-3); Group B (n = 8) received the control emulsion Intralipid ® Fresenius Kabi (100% LCT). Lipid emulsions were administered during 12 h at a dose of 0.12 g/kg/h. Measurements of the main hemodynamic and gas exchange parameters were made at baseline (immediately before administration of the lipid emulsions), every hour during the lipid infusion, at the end of administration, and six hours after the end of administration lipid infusion. Results. No statistically significant changes were observed in the different hemodynamic values analyzed. Likewise, the gas exchange parameters did not show statistically significant differences during the study. No adverse effect attributable to the lipid emulsions was seen in the patients analyzed. Conclusion. The lipid emulsion enriched with omega-3 fatty acids was safe and well tolerated in short-term administration to patients with ARDS. It did not cause any significant changes in hemodynamic and gas exchange parameters. Trial registration. ISRCTN63673813. © 2008 Sabater et al; licensee BioMed Central Ltd.