Objective: To report a case of Endometriosis associated with Pleural effusion. Design: Case report. Setting: Tertiary care center. Patient(s): A 30-year old woman presented with a right pleural effusion complicated with pneumothorax-mimicking TB. Intervention(s): Thoracentesis, pleural biopsy by a video-assisted thoracic surgery, pleurodesis, thoracic wedge resection, CT chest, CT Abdomen, and diagnostic Laparoscopy. Main Outcome Measure(s): After taking a GnRH analog, there was no recurrence of pleural effusion nor ascites. Result(s): Thoracentesis and wedge resection of lung ruled out malignancy. An omental mass biopsy obtained from diagnostic laparoscopy after the patient returned with drug-induced hepatitis, and ascites revealed endometriosis. Conclusion(s): Thoracic endometriosis is rare;however, it should be considered in the differential diagnosis by unknown causes of pleural effusion in reproductive age timeframe in women.