A 63-year-old man was admitted to Jikei University Hospital, with anasarca, and dyspnea in May, 2004. Echocardiograms and CT scans showed massive pericardial effusion, nodules on the pericardium and a tumor in the lower lobe of the left lung. Pathological examination of the punctured pericardial effusions yielded a diagnosis of pericardial malignant mesothelioma. However, no pathogen or malignant cells were identified from multiple biopsy specimens of the lung tumor, which were obtained by brochoscopic techniques. Since he worked as a fisherman in a diesel-powered fishing boat, he was possibly exposed to asbestos. On autopsy, the lung tumor was diagnosed as a primary lung adenocaricinoma. Exposure to asbestos is an important risk factor for both mesothelioma and lung cancer. However, pericardial malignant mesothelioma in itself is rare among mesothelioma. This is only the second report of malignant mesothelioma with primary lung adenocarcinoma, to date.