A 27-year-old woman presented with fatigue and dyspnea and was found to have a 2 x 4-cm mass in the pericardium, which was resected. Histologic examination demonstrated a well-differentiated papillary mesothelioma of the pericardium. Postoperatively, she received radiation therapy and had no evidence of recurrence 28 years later. It is extremely rare for this indolent variant of mesothelioma to arise in the pericardium.