Ultraviolet radiation (UVR) is the most important risk factor for skin cancer. Indoor tanning, defined as the use of an ultraviolet emission device to produce a cosmetic tan1, has been associated with increased risk of melanoma and non-melanoma skin cancer (NMSC), and thus has been classified as a group I carcinogen by the International Agency for Research on Cancer2. Despite the risk posed by this activity, indoor tanning is common practice among young people in developed countries. A systematic review and meta-analysis of 12 studies of indoor tanning and NMSC showed that ever exposure to indoor tanning was associated with a higher risk of both, squamous cell carcinoma and basal cell carcinoma, and that exposure at a young age (< 25 years of age) increased these risks considerably1. Since indoor tanning is a potentially modifiable exposure to UVR it would be relevant to examine its frequency and the characteristics of its users in the ALSPAC cohort. For the most part ALSPAC has not included questions regarding indoor tanning. The exceptions are the mother’s ‘Your environment’ questionnaire administered in early gestation asking how often they had used a sun bed or lamp during their pregnancy, and the child-based KN questionnaire at 69 months old asking about ever use of sun bed or lamp and its frequency. On the other hand, ALSPAC children have been assessed with respect to natural sunlight exposure at regular intervals, although only up to the age of 12 years.