BACKGROUND: Epidemiologic research shows that being sunburnt as a child is an important risk factor for cutaneous malignant melanoma (CMM). The purpose of this study was to investigate sunburn in relation to tanning habits and complexion among 7-year-old children living at different latitudes in Sweden. METHODS: Two municipalities were chosen at latitudes 65 degrees N and 68 degrees N in the north of Sweden and two at latitude 57 degrees N in the south. Children born in 1994 and registered in the municipalities were to be included (N=1676). A questionnaire was sent to their parents asking about their children's tanning habits, and the children were examined. The analysis set comprised 1360 children who participated in the examination and whose parents answered the questionnaire (81.1%). RESULTS: Twelve percent of all children had been sunburnt during the first 2 years of life compared to 44% between 2 and 4 years and 67% after 4. The children in the south at latitude 57 degrees N compared to Kiruna at latitude 68 degrees N and Piteå at 65 degrees N had a higher risk of ever being sunburnt during the first 2 years of life OR=1.87 (95% confidence interval (CI) 1.11-3.14) and 1.66 (0.95-2.90), respectively. The differences diminished with age. Sunscreen was an independent risk factor of being sunburnt between 2 and 7 years of age (not or seldom using sun screen was protective). Photosensitive skin type was the main risk factor for sunburns. CONCLUSION: Swedish children are frequently sunburnt and children living in the south are more sunburnt than those in the north. Sunscreens that were seldom used or not used at all were found to be protective. These results support previous reports that photosensitive skin type is an important risk factor for suffering sunburn as a child and therefore increases the risk of cutaneous malignant melanoma.