The use of radiographic imaging as an aid in diagnosis and treatment planing of periodontal disease is widely accepted. Its main purpose is to assess the level of the alveolar bone including the pattern and extent of bone resorption. Radiographs can provide critical information for diagnosis and treatment planing, which can also serve as baseline information for the assessment of treatment outcomes. Computer based image acquisition and processing technique now increase the importance of radiography in periodontal diagnosis. This article reviews various imaging modalities along with an analysis of their clinical application.