Chlamydia trachomatis (CT) infection is the most frequent notifiable sexually transmitted infection (STI) in Switzerland. The infection is most frequently observed in 15 to 24 year-old-women and in 25 to 34 year-old-men. 50-75 % of the Chlamydia trachomatis carriage are asymptomatic, making the infection difficult to diagnose and increasing the untreated specimen, leading to complications like infertility, ectopic pregnancy or pelvic inflammatory disease. Despite having a sexual prevention at school, the youths seem to have a lack of knowledge about CT, her transmission and her complications. We performed a survey, which showed that 60.5 % of the participants ignored that this bacteria is mostly asymptomatic. We also found that 11 % of the participants believed that there is no possible relapse of the infection. The prevention must be strengthened, mostly because there is no program in Switzerland, letting every physician to his own beliefs. The medical consultation is an ideal opportunity for this prevention and the youths shared their wish to discuss more about it with health professionals.