In five lung biopsies from patients who developed the clinical picture of Adult Respiratory Distress Syndrome (ARDS) after cardiopulmonary bypass the pulmonary alterations were studied morphologically and glucocorticoid receptors determined. The time between cardiac surgery and pulmonary biopsy was 4-7 days. The results showed severe pulmonary lesions, with marked endothelial damage and active collagen secretion in the pulmonary interstitium, along the capillary bed. The glucocorticoid receptor level of the lungs with ARDS was 4.7 +/- 7.04 fmol/mg protein (control 4.28 +/- 4.32 fmol/mg protein). The results indicate that the process of collagen secretion may begin in the early phase of ARDS and that the benefits of glucocorticoid therapy in the management of ARDS should be reassessed.