Imaging-guided percutaneous chest biopsy is a commonly performed procedure and considered the minimally invasive gold standard for histopathological investigation of thoracic masses. Recognized complications include pneumothorax, air embolism, and seeding of the biopsy tract. We describe a novel approach to diagnostic sampling of a mediastinal mass in a critically unwell patient using a transjugular hepatic biopsy needle. Transcaval mediastinal biopsy may represent a safer alternative to percutaneous biopsy of mediastinal masses in critically unwell patients.