Background and Objectives: Dental clinic and laboratory are environments where infectious diseases' transmission occurs easily and prevention of cross infection between these places is a crucial issue in dental practice. The purpose of this study was to evaluate the knowledge of general dentists about infection control of dental impressions between clinic and laboratory in south Khorasan province. Methods: In this cross -sectional study that done in 2014, the knowledge of dentists was assessed through a questionnaire consisting of twenty questions. For any questions a score from zero to two was awarded. For data extraction, scores of responses to each question were added together and the average was presented. For scores more than 34 good knowledge, between 25 and 34 moderate knowledge and less than 25 weak knowledge were reported. Level of dentists' knowledge based on their gender, work experience and university was also assessed. Data were analyzed by statistical software SPSS 16 in which Kruskal -Wallis and MannWhitney tests were used.