Cholesterol-lowering statins can ameliorate severe forms of vascular hyperper-meability in experimental studies, and may thereby amellorate acute lung injury and sepsis. It is unknown whether this also applies to humans. This study aimed to define whether or not prior statin therapy reduces mild post-operative increases in pulmonary capillary protein permeability associated with acute lung injury after cardiac or major vascular surgery. A prospective observational study was performed in an intensive care unit of a university hospital on 64 patients, 37 after elective cardiac and 27 after major vascular surgery, of whom 68 and 44%, respectively, had received prior statin therapy. A mobile probe system was used to measure the pulmonary leak index (PLI), i.e. the transvascular transport rate of gallium-67-radiolabelled transferrin. For all of the patients together, the mean PLI did not differ between the statin and control groups (22.9 versus 24.4 × 10-3 min-1). The prevalence of an elevated PLI was 57% in the statin and 59% in the control group. Subgroup analysis did not reveal significant differences caused by statins in the PLI of these patients. Prior statin therapy neither has an adverse effect on mildly increased pulmonary capillary permeability in patients after cardiac or major vascular surgery nor does it ameliorate this increased capillary permeability.