Objectives: Describe the knowledge, attitude and practice about sexual transmitted infections of students at Nguyen Binh Khiem high school - Hai Duong city in 2013. Methods: cross-sectional description. Results: Percentage of students know that HIV/AIDS is a sexual transmitted infection quite high (85.4 percent), the percentage of students know that hepatitis B is very low (4.5 percent). Percentage of students have discriminatory attitudes towards those sexual transmitted infections is quite high (38.6 percent of students said that should stay away from people who have transmitted sexually). Percentage of students who have sexual transmitted infections go to health facilities to diagnose and treat is low (19.5 percent). Conclusion: Student's knowledge about sexual transmitted infections is limit. Need to further enhancing life skills education, providing information about reproductive health for high school students.