As part of the national skin cancer prevention programme coordinated by the Swiss League against Cancer, a mobile unit visited 29 Swiss towns to inform people on skin type, skin cancer risk and sun protection behaviour. In the summer of 2003, among 6725 visitors, 3662 took the offered possibility of having a cutaneous lesion checked free of charge by a dermatologist present in the mobile unit. The campaign satisfactorily covered, albeit to various degrees, its 3 fields of activity, i.e. (1) primary prevention, (2) secondary prevention and (3) clinical examination. Participants were predominantly females (60%), except for visits on work sites (firms and universities), half were aged 15-44 years, and 40% were considered at increased risk for skin cancer. Sociodemographic and regional differences in the profile of visitors were observed and could largely be attributed to variations in daily availability of the mobile unit. 108 malignant lesions were observed, including 21 cutaneous melanomas. Relative to the number of examinations performed, more cancers were detected in men, those aged 65 or over, and visitors who experienced a prior skin screening and severe sunburns during childhood. Limitations and prospects of this type of preventive campaigns are briefly discussed.