Organ transplantation remains the best treatment for many patients with end organ disease. However, there is a discrepancy between organ supply and demand. Many donor organs are not used for transplantation because of risk attributes in the deceased donor ranging from infectious risks to specific risks associated with the cause of death. The aims of this thesis were to identify the number of deceased donors with risk attributes and then quantify the risks associated with using organs from such donors. This information was then used to provide evidence to the transplant community on which to base their decisions on using organs from such donors. This thesis used data in the UK Transplant Registry, which prospectively collects data on the clinical characteristics and follow-up of all donors and transplant recipients in the UK, and the Potential Donor Audit, which is a prospectively populated registry including all patients who die in UK critical care units of donation age. The main findings of this thesis were that there are a large number of deceased donors with risk attributes, in particular donors with increased risk behaviour for blood borne viral disease or with hepatitis C virus infection, whose organs are currently not used for transplantation, but that could safely be used. The thesis also describes that the transmission of meningitis/encephalitis from deceased donors to transplant recipients is a rare but serious complication of transplantation, but that transplantation of usually excellent organs from such donors should not be contraindicated. Different transplant centres display marked variations in practice in using organs from donors with different risk attributes, but centres that display greater risk appetite in using organs from higher risk donors do not have worse transplant outcomes compared to centres with lower risk appetites. Transplantation of organs from higher risk donors can result in excellent transplant outcomes. Wide variations in practice are seen across the UK, and to address this the UK aide memoire has been developed.