We report the case of a patient in which thiazolidinediones (TZDs) were associated with recurrent pleural effusions post coronary artery bypass surgery, in spite of a normal left ventricular function. The potential mechanisms are discussed, particularly in relation to the "vascular leak syndrome". This finding has important implications for the management of diabetic patients who are referred for coronary artery bypass surgery and who are on TZDs for glycemic control.