Background and objective: The use of modern diagnostic methods and techniques in dentistry has caused huge changes in patient treatment modality. One of the most important diagnostic techniques in dentistry is radiography. To be beneficial to patients, it requires dentist sufficient knowledge of its use. The aim of this study was to evaluate knowledge of Zanjan dentists this topic.

  Material and Methods : This was a descriptive cross-sectional study. The test group consisted of 44 dentists (general and specialized) practicing in both governmental centers or private offices in Zanjan.

  Results: The results of this study showed that of 20 questions in the questionnaire, the lowest score was 5 and the highest was 18 with the mean of 11.5 and the standard deviation of 3.25. In the test group, 9.1% were well-informed, 7.3%were moderately, and 13.6% were less-informed about the subject. There was no significant statistical relationship between knowledge of x-ray use and the level af academic experience, the year of graduation and sex.

  Conclusion: The results of this study showed the importance of offering regular in-sevice courses for maintaining and enhancing dentists ' knowledge and introducing new diagnostic and radiographic methods.