In the randomized controlled trial, female smokers aged 14-25 will be recruited in practices of gynaecologists. Intervention within the practice consists of a 30 minutes counseling session based on Motivational Interviewing, a standardised physician letter focusing on the elevated health risks of smoking while using hormonal contraceptives and a stage-matched self-help manual. After four weeks, an expert system feedback letter will be sent. In the intervention group, no smoking intervention will be given. Follow-up assessments will be conducted after 12 months, including saliva cotinine measures.