To evaluate the long-term effect upon oral health knowledge and reported behavior of a comprehensive and a less comprehensive preventive program given to 13-16-year-old children 5 years after the termination of the programs. 186 Brazilian schoolchildren, randomly assigned to two test groups and a control group were originally enrolled in a 3-year preventive program. The comprehensive program included active participation of the students and their parents. The time resources invested in this program were approximately 5 times that of the less comprehensive program, which mainly consisted of instruction in oral hygiene procedures. At the end of the program, a questionnaire was filled in by the participants showing a significant effect upon both knowledge and reported behavior of both programs; the comprehensive program displaying the better results. Five years later, the same variables were re-examined through a structured telephone interview with 103 of the original participants. Significant differences in knowledge among the three groups were still observed, but not in reported behavior. In all groups the reported daily users of dental floss increased with time and the number of daily in-between-meal consumers of sugar decreased. Females reported more frequent daily use of dental floss than did males five years after the termination of the program, but this was not evident immediately after the experimental period. After 5 years, the correlation between knowledge and reported behavior was no longer significant. Other factors than knowledge are of importance for behavior, and favorable behavior in early adulthood may be achieved independent of implementation of programs for teenagers. Keywords: oral health education, adolescents