Meffert and Anthony1 claim in their letter that the association of human papillomavirus (HPV) type 7 with butcher's warts is misinformation. They argue that the only publication on this issue, by Orth et al2 in 1981, actually found that HPV-2 was more commonly associated with butcher's warts than HPV-7. The alleged absence of any other published evidence led them to doubt the existence of a privileged link. I wish to respond to their 2 questions: "How do we know?" and "Are we sure?"