The aim of the study is to determine awareness about sexually transmitted diseases (STDs) and their prevention in people aged 14-19 of Ferrara and province. The study was carried out using a self-administered standardised anonymous questionnaire in a sample of students attending to three upper secondary schools. Total number of collected questionnaires was 2695, the average age of interviewed was 17.1. Only 52.3% of respondents correctly recognized STD definition. Over 95% of subjects identified acquired immune deficiency syndrome (AIDS), while properly classification of Hepatitis B increased with age and lowest degree of knowledge concerned herpes infection and Candidiasis. Sex without condom (95.97%) and needle exchange in drugs abusers (94.9%) are considered high risk behaviours. 80.3% of interviewed, without distinction of school attendance, sex, and age considered lack of information as a situation of high risk. Condoms are not used by 46.4% of the subjects in case of sex with a regular partner and by 9.5% with casual partner. Majority of students declared condoms very safe in preventing STDs but an important percentage indicated also contraception methods; correct answers were higher among females and increased with age. Main sources of information were TV (21.6%), school (21.1%) and friends (14.8%) and a few sought information from family doctor (7.4%) and web (4.8%). The study suggests, as priority, to improve teenagers' awareness about risk behaviours and prevention of STDs. School can play an important role in reinforcement of sexual education programmes and directing young people to general practitioners and primary sexual health care services.