Hand warts were studied in 160 butchers. Clinical and histological studies were performed in 190 warts and virological studies in 165 warts from 104 butchers. Since we found almost perfect correlation between the histological pattern and the type of infecting virus, it was possible to evaluate the virus types in a further 39 of 56 butchers without virological studies, on the basis of the histology of the warts. The most common infection was with HPV-2 (human papilloma virus) and HPV-7. Thirty-three butchers were infected with two types of viruses and three butchers with three HPVs. The morphology of warts varied considerably. The majority were similar to verrucae vulgares or verrucae planae. Some deep warts resembled myrmecia-type verrucae plantares. Often, several types of warts coexisted. Some clinical patterns were shown to be preferentially associated with distinct types of papillomaviruses: common warts with HPV-2, HPV-4, or HPV-7, plane and intermediate warts with HPV-3, HPV-10, HPV-28. HPV-7, previously identified for the first time in these butchers, was found to be associated with common warts or common wart-like, papillomatous lesions.