Therefore, providing knowledge, attitude and practice for dengue hemorrhaged fever prevention for students is a necessary operation. Objectives: The study aimed to evaluate the knowledge attitude and practice of prevention on dengue hemorrhaged fever, before and after project interventions to prevent dengue hemorrhaged fever in Tan Hung high school, Cai Be district in Tien Giang province in 2009.Methods: Study design before - after, to investigate knowledge, attitude and practice on dengue hemorrhaged fever prevention, and in combination with the investigation of the vector of dengue hemorrhaged fever transmission in households of the study. Results: In this study, students receive information on dengue hemorrhaged fever from teachers is 81.2% after the intervention is 98.4%.