Objective: To explore attitudes towards two-wheel motorized vehicle (TWMV) helmet use among adolescents in a country with poor legal compliance. Design: Self-administered questionnaires were completed by 523 high school students to define the sample of a qualitative study; thereafter, the Health Belief Model (HBM) was applied in 12 focus groups comprising 70 students. Setting: Three randomly selected public secondary schools in middle-income areas of Athens, Greece. Results: Students reporting frequent helmet use were characterized by a high perceived threat of a TWMV-related injury, which seemed to be associated with both prior experience of an injury and receiving information on helmet wearing from "significant others." Students reporting helmet non-use were characterized by a low threat perception, possibly attributable to adolescent egocentrism and accompanying feelings of invulnerability or to lack of knowledge and experience in risk identification. A sharp contrast was noted regarding the most important perceived benefit of helmet use, expressed among users as "protection in the case of a road crash" and among non-users as "avoiding tickets from traffic police". Main barriers to helmet use, as identified by non-users, included: low perceived efficacy of helmets; peer pressure; lack of appropriate information on helmet use; high helmet cost; lack of convenience; vision and hearing disturbance; and style reasons. Conclusions: When social norms of low compliance to safety laws prevail, qualitative research can assist in developing tailored educational interventions targeting behavior modification among adolescents.