Lung cancer during pregnancy is a rare condition. We report a case of 28-year-old nonsmoker female, who was admitted to our hospital with massive left pleural effusion in the 21st week of gestation. Chest radiograph showed total left hemithorax opacity with contralateral mediastinal deviation. Pleural biopsy and cytological examination of pleural fluid revealed adenocarcinoma invasion with positive epidermal growth factor receptor mutation status. Cesarean section was performed at 32 weeks of pregnancy, and targeted therapy was given to this patient after delivery. Computed tomography of the thorax showed a mass lesion in the left hemithorax with liver metastases. Unfortunately, the patient died 10 days after delivery. © 2017 Indian Chest Society | Published by Wolters Kluwer -Medknow.