The aim of this paper is to provide an effective and comprehensive summary of the main inflammatory pleural diseases, providing the radiologist an overview of key points in CXR, CT and US, and their main aspects in the differential diagnosis. The diffuse benign pleural diseases are frequently found during the first-level radiological diagnostic approach, but they are often difficult to classify because of their poor characterization. Pleural effusion or thickening can have a benign or malignant cause and use of the appropriate imaging techniques is crucial to a correct diagnosis. The clinical features of pleural disease are often nonspecific and may require complex imaging and histology for diagnosis. The integration of informations derived from different methods (CXR, CT and US) is extremely important to an appropriate diagnosis.