There are different types of methods used in determination of working length in endodontics. Working length determination is very important step in endodontic procedure. Radiographs, tactile sensation, the presence of moisture on paper points, and knowledge of root morphology have been used to determine the length of root canal systems. Nowadays electronic Apex locators are used for working length determination.The different generations of electronic Apex locators are introduced till now for the working length determination.