Adolescents constitute an important audience for photoprotection programs. Sun exposure and sun protection habits acquired during adolescence have a significant impact on skin cancer incidence. We administered a questionnaire to 724 students about ultraviolet radiation effects, opinions about tanning, total time of sun exposure per day, photoprotection and activities in the sun. About 90% were aware of the association between sun exposure and skin cancer, and mass media was the main source of information. However, the great majority believed that tanning improved their appearance, and that it was worth taking the risk. The most prevalent outdoor activity among boys was sports; girls preferred walks and sunbathing. Sun exposure was significantly longer in summer, when 90% of the students went to the beach. About 47% reported sunscreen use in summer and only 3% reported using sunscreen during winter. These results emphasize the need for the promotion of photoprotective habits in our population and the importance of engaging physicians and schoolteachers in developing campaigns directed at this issue to achieve effective, long-lasting results. Adolescents are aware of the effects of ultraviolet radiation on the skin but campaigns have not successfully changed their sun exposure habits.