Southern travelling habits were recorded for 127 melanoma patients from southern parts of Sweden (the 56th latitude), 55 thyroid cancer patients, 100 non-Hodgkin's patients and 794 healthy controls from the same region. Melanoma patients were found to travel significantly more often south of the 45th latitude, as compared with patients with non-Hodgkin's lymphoma or thyroid carcinoma (RR = 2.2 for a difference of + 10 trips), and with the healthy controls (RR = 1.4 for a difference of + 10 trips). Considering men and women separately, the difference was significant only for men. Patients with melanoma had a higher educational level than the tumour controls and the healthy controls (p < 0.001 and p < 0.001 respectively). There was a significant correlation between high travelling frequency and high education. An increased risk related to southern travelling was present for patients with melanoma on the extremities and head and neck, as well as for patients with truncal melanoma. These findings support the concept that acute exposure to sunburn may be a risk factor for malignant melanoma.