We studied 56 cases of malignant pleural mesothelioma (MPM) treated with extrapleural pneumonectomy (EPP). The slides from the EPP specimens were reviewed, and tumors were classified with the guidance of the World Health Organization classification of pleural tumors. Agreement between the histologic type from the EPP review and the diagnostic procedure (DP) reports was evaluated. Histologic and clinical parameters were also correlated with clinical outcome. There was a significant disagreement (P = .0001) between the histologic type in the DP reports and the EPP specimen review. The histologic type from the DP was associated with disease-specific survival (DSS); however, the histologic type from the EPP specimen was not associated with survival. Postoperative treatment was associated with DSS and with recurrence-free survival. Our study confirms that in many cases, final histopathologic typing of MPM is influenced by complete surgical resection and that initial biopsy should be carefully weighed in the treatment stratification.