The determination of an accurate working length is one of the most critical steps of endodontic therapy. The radiographic method has been the standard means of determining the working length.Number of circumstances make this less than ideal method as it is impossible to consistently detect the major and minor foramina or cemento-dentinal junction (CDJ). Electronic root canal measuring devices were developed to reduce the number of radiographs during the treatment, improve the accuracy of the root canal measurement and to save time during the procedure. Many studies have shown that the current generation of electronic devices are accurate between 82-92% when compared to radiographically determined root canal lengths. A study was done evaluate the accuracy of working length determined using conventional radiograph followed by apex locator in the same tooth and comparing these findings post extraction with the natural apical constriction, after decalcifying the tooth. A stereomicroscope and image analysis unit was used to measure the differences and the results were tabulated and analyzed.