Sixteen, patients with malignant mesothelioma of the pleura .were evaluated, retrospectively. Malignant mesothelioma of the pleura most commonly occurs in persons with a heavy exposure to asbestos. But, except two cases, these patients have no such history of exposure. All patients had unilateral typically exudate pleural effusions. And most of them were hemorrhagic. The diagnosis was made by closed pleural biopsy with Cope needle in patients, and by open pleural biopsy in six patients. The six-teen mesotheliomas consisted of nine epithelial, two sarcomatous and five mixed types, pathologically. Median survival was approximately 13 months.