CT features are described and accuracy of the method is discussed in the diagnosis of malignant pleural mesothelioma. Ninety-eight patients suffering from pleural disease mimicking mesothelioma were examined by means of III-generation CT scanners; according to the final diagnosis, 37 patients suffered from malignant pleural mesothelioma, 27 from other malignant pleural diseases and 34 from various benign diseases. In all patients a series of CT signs was evaluated: pleural thickening patterns, lesion spread and possible associated characters. In the diagnosis of mesothelioma CT showed 72.5% sensitivity, 63.8% specificity, 68.3% diagnostic accuracy, 68.5% positive predictive value and 68.2% negative predictive value. Some significant CT patterns in distinguishing malignant from benign pleural disease were identified, while the characterization of malignant disease (mesothelioma versus other neoplastic conditions) proved to be unreliable.