objectives there were determined: risk factors, knowledges, attitudes and practices in the teenagers of high school from the 2 and 4 nuclei between july and november of 2003, were determined. methods descriptive transversal study. through a bietapic method, with a cap formulary there were inquired 751 teenagers between 14 and 19 years in 9o, 10o and 11o grade from schools that belong to the 2 and 4 educational nuclei in barranquilla. results a 42.8% dont know exactly the related with hiv/aids, 1.2% males and 0.6% females have a refuse attitude for the condition. 34.8% said that they are not virgin, and there were found association between genre and to have had more than one sexual partner ant to have had relations with stranges (p<0.05) (22%). majority of male (73.9%) and female (67.1%) don？t use preservative everytime, 37.3% thinks that their risk of infection is nule and 34.6% don？t know it, but many of them have risk factors. conclussions many teenagers don？t have enough knowledge about aids-hiv, they have a good attitude in the managing of the theme, but they have risk factors to be infected unknowing their real risk. is necessary to teach trough to modify risk practices in this population. key words: risk factors, knowledge attitudes and health practices, teenager？s behavior, hiv-aids, hiv infection.