Background : Radiographs are used to diagnose and monitor oral disease or therapeutic prognosis. 25% of the interpreted periapical radiograph bisecting technique is unacceptable for diagnostics. Failures that may arise include artifact in the radiograph, blur image, cropped images, distorted image, and forshortening and elongation of images. Objective : The purpose of this study was to know percentage of radiograph periapical bisecting tecnique error type at RSGM UMY accepted by UMY clinical dental students year 2015. Method : Using description method with cross-sectional pattern. Samples were taken by using total sampling at UMY clinical dental students year 2015 in May 2017. The data collection using questioner contains 24 statements with Likert’s modified scale. Result : The type of errors that happened in RSGM UMY on “often” and “sometimes” scale are a) backward positioning (13,8%), b) overlap (67,5%), c) no object in the film (17,5%), d) film misplacement (73,8%), e) artifact (31,3%), f) finger marks (17,5%), g) blur image (91,3%), h) double exposure (11,3%), i) cone cutting (75%), j) dark radiography (83,8%), k) light radiography (73,8%), l) distortion (83,8%), m) elongation (75%), n) forshortening (72,5%). Conclusion: The highest score on statement “often” is about blur image with total 14 resondent from 80 responden or 17,5%. The lowest score gets from double exposure with total only 9 respondent or 11,3% on statement “sometimes”.