Radiographic examination aids in the many steps of endodontic treatment, from diagnosis and treatment planning to assessment of outcome. The amount of information gained from conventional film and digitally captured intraoral radiographs is invaluable, but also limited. To some extent, particular clinical and biological features may not be reflected in radiographic images, because the three-dimensional anatomy is compressed into a two-dimensional image. This results in the superimposition of anatomical structures onto the features of diagnostic interest, sometimes to the extent that the latter become concealed. Therefore, the presence of a lesion may not be directly evident, and its real extent and the spatial relationships to important anatomical landmarks are not always easily visualised. There may also be geometric distortion of the anatomical structures being imaged. Also, exposure parameters, image processing, viewing conditions, and the training and experience of the human observer all affect the quality of radiographic examination. This paper reviews some aspects of the usefulness and limitations of the radiographic examination in periapical diagnosis. Keywords: apical periodontitis, radiographic techniques