IntroductionPleural exudative effusions without diagnosis after initial work up are a frequent problem in any respiratory division. Several ways to obtain pleural biopsy exist. Thoracoscopy is one of the most frequently used. Differential diagnosis mainly exists out of malignant pleuritis, tuberculosis, nonspecific pleuritis and rarely systemic or autoimmune disease. We performed a retrospective data analysis of our almost 10-year period experience, the first Belgian data to be published.MethodsWe performed a retrospective data analysis of all patients with unexplained pleural exudates who underwent diagnostic medical thoracoscopy under general anaesthesia in our respiratory department during the period 2006–2015. We report on diagnoses made, sensitivity and specificity, safety of thoracoscopy and follow-up of patients after thoracoscopy.Results131 patients underwent diagnostic medical thoracoscopy during the inclusion period. 44.3% (n=58) of the patients were diagnosed with malignant pleuritis, 45.0% (n=59) with nonspecific pleuritis, 7.6% (n=10) with tuberculous pleuritis and some with other benign conditions. Complications are comparable to other data published. Six months follow-up of patients with non-specific pleuritis reveal 8.5% (n=5) of these patients to have malignant pleuritis, and another 8.5% (n=5) with infectious or other benign conditions.ConclusionMedical thoracoscopy under general anaesthesia for diagnostic work up of pleural exudates of unknown origin generally has a high diagnostic yield. It is generally safe, certainly compared with the information it delivers. During follow-up, minority of patients with nonspecific pleuritis will prove to be malignant in origin, benign or autoimmune disease related.