SummaryWe present two patients with moderate left ventricular dysfunction, who developed a pleural effusion after coronary artery bypass grafting (CABG). The effusion was proven to be an exsudate of tuberculous origin. This illustrates that not all pleural exsudates developing after CABG are due to a post-pericardiotomy syndrome. Therefore microbiological examination of pleural fluid and if necessary pleural biopsy should be performed in all patients with an unresolving pleural effusion following CABG.