An unequal distribution of cancer laterality, particularly in paired organs, has long been documented and generally thought to be related to asymmetries in organ size or behavioral factors such as handedness.1 Recently in a large series patients with cancers in the left testis, right lung, and left ovary were found to have a significantly better survival than those with contralateral cancers.2 Apart from anecdotal assertions and very sparse data that suggest asymmetrical differences in the frequency of cutaneous melanoma and photodamage,3,4 melanoma laterality has, to our knowledge, never been specifically studied. Investigation of laterality could thus contribute to a better understanding of cancer etiology and prognosis.