A surgical series of 23 patients with pleural mesothelioma is reviewed. Three who had benign localized mesothelioma of fibrous type are alive and well at least 10 years postoperatively. In two others, radically extirpated localized mesothelioma was histologically classified as benign, but later proved to be malignant, causing death from recurrent disease 27 and 79 months postoperatively. Four patients with diffuse malignant mesothelioma underwent pleurectomy or open biopsy and survived for 2-9 months. Radical en-bloc pleuropneumonectomy was performed on 14 patients with diffuse malignant mesothelioma. One patient died postoperatively and the others succumbed to the disease after 3-51 (mean 20) months. The survival time was greater than or equal to 1 year in 62% of the patients and greater than 3 years in 23%. Patient age, histologic tumour type and extent of disease seemed to be important prognostic factors. Despite the generally poor prognosis, the results of radical surgery in this study appear to warrant an aggressive approach to treatment of benign or localized malignant pleural mesothelioma, and possibly also to stage I diffuse malignant mesothelioma of epithelial type.