Transplant-related malignancies are a major contributor to morbidity and mortality in the organ-recipient population, and most often develop de novo in the immunosuppressed recipient or as recurrent malignancy after transplantation. The least common scenario, and a rare event, is a recipient malignancy derived from the donor organ. Melanoma is one of the most often reported and lethal donor-derived malignancies with a high transmission rate. Donor transmission of melanoma might be related to the biology of melanoma, with regard to tumour dormancy, late recurrence, circulating tumour cells, and the destiny of some micrometastases. Melanoma-cell dormancy explains the late recurrence that can occur after the initial treatment of melanoma, and may be relevant to our understanding and management of some melanoma micrometastasis in the sentinel node. The high incidence of circulating tumour cells in early melanoma should be considered in the context of the transmission of melanoma by apparent disease-free organ donors following removal of a primary melanoma up to 32 years before. This scenario suggests that melanoma cells can remain dormant at distant sites for decades (and possibly forever) in immunocompetent patients, only to reactivate after transplantation into an immunosuppressed recipient. Potential organ donors should be carefully screened for a history of melanoma, and excluded. The current recommendation for treatment of donor-related melanoma includes withdrawal of immunosuppression, graft rejection, and explantation of the allograft after rejection has been established. In non-renal transplant patients with life-sustaining organs, withdrawal of immunosuppression and graft rejection is not feasible, and reduction of immunosuppression or urgent retransplantation are the only possible salvage strategies. The transmission of malignancy by organ donation could be considered "nature's own experiment", but raises questions that our current understanding of the biology of melanoma cannot answer.