Adolescents' sexual behavior is the focus of attention since increased levels of unintended pregnancy, abortions and sexually transmitted diseases are detected. Psychological, family and social factors contribute to the above mentioned situations. The aim of the present research was to examine the intention of condom use in adolescents of both sexes using the Theory of Planned Behavior. Material- Method: The study population consisted of 378 adolescents, aged 15 to 18. Data was collected by the completion of a questionnaire based on the Theory of Planned Behavior. The statistical method used was x2, t-test, one-way ANOVA. The data statistical analysis was carried out using the SPSS 13.0 program. Results: From the participants, 94.9% reported that they had sufficient knowledge on contraception issues. Friends were the main source of information (20.2%). The majority of adolescents (58.2%) had full sexual intercourse at age 15 (30%). Proportionally, adolescents with higher self-efficacy were found to have greater intention to the condom use. The more increased was the degree of the convenience in using condom with a new partner, the more positive was the adolescents' attitude towards the use of condom with a steady partner and the greater was the degree of awareness about sexual issues, the greater the behavioral intention. Conclusions: The degree of the adolescents' self-efficacy, in other words, the more confident they are in their abilities and skills of overcoming possible obstacles, the greater their intention to use condom. According to the results, the factors which strongly predict the intention, in order of importance, were: self – efficacy, degree of control, degree of awareness and the descriptive regularity. The findings are of great importance for the Hellenic science, since there is insufficient and little data on this subject.