Background. To better define the risk of malignancy transmission through organ transplantation, we review the Spanish experience on donor malignancies. Methods. We analyzed the outcomes of recipients of organs obtained from deceased donors diagnosed with a malignancy during 2013–2018. The risk of malignancy transmission was classified as proposed by the Council of Europe. Results. Of 10 076 utilized deceased donors, 349 (3.5%) were diagnosed with a malignancy. Of those, 275 had a past (n = 168) or current (n = 107) history of malignancy known before the transplantation of organs into 651 recipients. Ten malignancies met high-risk criteria. No donor-transmitted cancer (DTC) was reported after a median follow-up of 24 (interquartile range [IQR]: 19–25) mo. The other 74 donors were diagnosed with a malignancy after transplantation. Within this group, 64 donors (22 with malignancies of high or unacceptable risk) whose organs were transplanted into 126 recipients did not result in a DTC after a median follow-up of 26 (IQR: 22–37) mo, though a prophylactic transplantectomy was performed in 5 patients. The remaining 10 donors transmitted an occult malignancy to 16 of 25 recipients, consisting of lung cancer (n = 9), duodenal adenocarcinoma (n = 2), renal cell carcinoma (n = 2), extrahepatic cholangiocarcinoma (n = 1), prostate cancer (n = 1), and undifferentiated cancer (n = 1). After a median follow-up of 14 (IQR: 11–24) mo following diagnosis, the evolution was fatal in 9 recipients. In total, of 802 recipients at risk, 16 (2%) developed a DTC, which corresponds to 6 cases per 10 000 organ transplants. Conclusions. Current standards may overestimate the risk of malignancy transmission. DTC is an infrequent but difficult to eliminate complication.