Radiological imaging methods are an important part of the diagnostic process for patients presenting with a disease of the paranasal sinuses. They allow a non-invasive approach to identifying congenital lesions, anatomic variations, injuries, inflammatory and neoplastic processes. Paranasal sinuses are air-filled cavities within the osseous structures of the skull, lined with a ciliated columnar epithelium. Narrow drainage pathways connect them to the nasal cavity. The patency of these pathways is crucial for their proper functioning. The close relationship of the paranasal sinuses to other structures of the skull is a predisposition towards a possible spread of the inflammatory or neoplastic disease to these surrounding structures. The paranasal sinuses are primarily evaluated with computerized tomography. It is the method of choice for identifying congenital diseases, injuries and chronic inflammatory processes without local spread of the disease. Magnetic resonance imaging is used to detect and stage tumors as well as evaluate the response to treatment. Computerized tomography and magnetic resonance imaging play complementary roles in assessing the extension of an infectious or neoplastic process beyond the paranasal sinuses. Computerized tomography shows the thin osseous sinonasal walls in excellent detail, while magnetic resonance imaging distinguishes abnormal soft-tissue structures more precisely and allows for early detection of the local spread of inflammatory or neoplastic processes.