As squamous cell cancer (SCC) is the most common malignancy in organ transplant recipients, a viral etiology has been proposed. Human papillomavirus (HPV) is found more often in organ transplant recipients than in the general population, but its role in cancer development has been debated for years. As a model of susceptibility of HPV the inherited disease epidermodysplasia verruciformis (EV) has been investigated intensively. EV is an autosomal-recessive skin disease leading to multiple flat warts and pityriasis versicolor-like macules in early youth. EV patients are at great risk of developing skin cancer due to a lack of defense against beta HPV. Beta HPV are causally involved in the formation of skin cancer in patients afflicted with EV. Beta HPV has frequently been detected in SCC and its early lesions such as actinic keratoses. Depending on the methods used, a prevalence of 30-90% has been reported for beta HPV for SCC in organ transplant recipients, while this prevalence in the general population is lower, but still considerable at 50%. Epidemiologic studies in the general population seem to suggest that beta HPV plays a role in the formation of SCC, both for invasive and in situ lesions.