Pulmonary carcinoma is uncommon after lung transplant, but doubtlessly affects recipient survival independently of other complications. Small cell lung cancer is much rarer after transplant than non-small cell lung cancer. We report a case of mediastinal small cell lung carcinoma confirmed by endobronchial ultrasound biopsy that occurred 18 months after a single lung transplant for interstitial pulmonary fibrosis in a 58-year-old male non-smoker. The patient died shortly after of distant metastasis. Our report confirms the usefulness of tumor markers and positron-emission tomography-computed tomography as routine tests for earlier detection of malignant disease after lung transplant.