Fourteen patients with adult respiratory distress syndrome were admitted to the medical intensive care unit and received bedside heart catheterization with the use of a balloon-tipped, flow directed catheter. Four of the 14 (29 percent) were found to have left ventricular failure (LVF), defined as a pulmonary artery wedge pressure greater than 12 mm Hg. Analysis of the standard clinical and laboratory data demonstrated no criteria which could differentiate those patients with LVF from those without. Three of the four patients indentified as having LVF responded to therapy directed toward LVF with substantial clinical improvement.