To investigate knowledge and practices towards preventive dentistry among undergraduate dental students and interns in Qassim university. 1. To assess the level of knowledge of preventive measures in dentistry among undergraduate dental students and interns in Qassim university. 2. To evaluate the practices of undergraduate dental students and interns in Qassim university in preventive dentistry. A ninety seven participants were involved in this study 28 third year students, 25 fourth year students, 24 fifth year students and 19 dental interns. The questionnaire was adopted from previous similar studies carried out in Nairobi dentists and Iranian dentists. Conclusions Based on the findings of this study, the following was concluded: 1. Undergraduate students and dental interns in Qassim University had vast knowledge towards preventive dentistry. 2. Undergraduate students and dental interns in Qassim University carried out most of the practices involved in preventive dentistry.