Objectives To find out whether there is a potential impact of the appearance of a plain cigarette package on the smoking perceptions and behavioural intentions of Flemish adolescents. Design We performed a cross-sectional study using the qualitative method of focus group discussions. Setting Flemish adolescents. Participants We performed eight focus group discussions, in which 55 adolescents took part, 32 female and 23 male. Inclusion criteria were: Flemish male and female 15-year-olds to 16-year-olds and 17-year-olds to 18-year-olds attending regular high-school education or vocational training who were current or had ever been smokers. Outcome measure (planned as well as measured) The opinions and perceptions of young Flemish smokers regarding the impact of cigarette packaging on their smoking behaviour. Results Plain packages are perceived as less attractive, cheap and unreliable for young people. Because of the unattractiveness of the plain packaging, the health warnings catch the eye much more strongly. Conclusions In this first scientific study in Flanders on this topic, it emerged that plain packaging could be a strong policy tool to reduce the number of adolescents starting smoking. Validation of these findings by conducting a quantitative survey in the same target group is recommended.