The life-long immunosuppressive treatment (IST) necessary to prevent allograft rejection in organ-graft recipients (OGR) puts them at high risk for developing various malignancies, namely those of viral origin. Among these, skin cancers are the commonest, accounting for over two thirds of cases. The prevalence of skin cancers increases with time post-transplantation, reaching 20–40% of OGR 20 years post-graft, depending on the country. Along with IST, several factors act as co-carcinogens, such as sun exposure and infection with (potentially) oncogenic viruses (such as HPV, HHV-8, EBV and MCPV). Other factors also play a role, such as the nature (kidney, heart, liver, lung) and origin (cadaveric or not) of the organ grafted, sex and age of the recipient and age at transplantation. The commonest skin malignancies are keratinocytic neoplasms, such as actinic keratoses, Bowen's disease and squamous cell carcinomas, the incidence of which is 60–100 fold higher than in the population at large. Basal cell carcinomas and Melanomas are also increased by a factor of ≈10. Kaposi's sarcoma (KS) is increased almost 500 fold vs controls, and its pathogenesis has been much better understood after the discovery of the responsible virus (HHV8) in 1994. Merkel cell carcinomas can affect OGR and the discovery of a new polyoma virus (MCPV) has shed light onto the link of this tumor with imunosuppression. Cutaneous lymphomas are rarer than systemic ones but may have a poor outcome. Although initially B-cell ones were more often reported, recent studies suggest that T-cell ones could be predominant. Several other skin malignancies have also been reported after organ transplantation (atypical fibroxanthomas, dermatofibrosarcoma protuberans, angiosarcomas, leiomyosarcomas, adnexal carcinomas…), but whether their relative risk is increased vs controls remains uncertain because of the rarity of these tumors in the population at large. The treatment of skin malignancies in OGR relies on the same modalities as in the population at large (surgery, photodynamic treatment, chemotherapy, radiotherapy), but the outcome may be poorer. Along with appropriate therapy, management of skin malignancies should include revision of the IST in order to minimize it. More recently introduced immunosuppressants (such as sirolimus) have been shown to decrease the risk of cancer development thanks to antitumoral/antiangiogenic properties. Better education of OGR about risk factors, resulting in better prevention, along with the introduction of safer and more efficient immunosuppressants will hopefully contribute to the decrease of the incidence of cancers in OGR.