The pericardium can be affected by infectious, neoplastic, inflammatory and metabolic diseases. Many conditions require specific treatment and, consequently, an accurate diagnosis is important. Therefore, the pericardial biopsy has an important role in the evaluation of pericardial effusions. The pericardioscopy offers the advantage of the traditional subxiphoid approach, as it allows access to parts of the pericardium that would not be reached by digital palpation, as well as direct visualization through the subxiphoid window or thoracoscopy. We report the case of a patient with a large pericardial effusion and an undiagnosed mediastinal mass, in which video-assisted pericardioscopy was fundamental in the diagnosis and treatment of the disease.