Background. The Netherlands has a low number of deceased organ donors per million population. As long as there is a shortage of suitable organs, the need to evaluate the donor potential is crucial. Only in this way can bottlenecks in the organ donation process be detected and measures subsequently taken to further improve donation procedures. Methods. Within a time frame of 4 years, 2005–08, medical charts of all intensive care deaths in 64 hospitals were reviewed by transplant coordinators and donation officers. Data were entered in a web-based application of the Dutch Transplant Foundation, both to identify the number of potential organ donors (including donation after cardiac death), as well as to analyse the reasons for potential donor loss. Results. In total, 23 508 patients died in intensive care units, of which 64% were younger than 76 years. The percentage of all potential organ donors out of the total number of deaths decreased from 8.2% in 2005 to 7.1% in 2008. Donor detection increased from 96% in 2005 to 99% in 2008. Of the potential donors, 17–21% recorded consent and 17–18% recorded objection in the national Donor Register. If the Donor Register was not decisive, the consent rate of families approached for organ donation was 35% in 2005, 29% in 2006, 41% in 2007 and 31% in 2008. The overall conversion rate (the number of actual donors divided by the number of potential donors) was 30%, 26%, 35% and 29% in these years. In the group of potential donor losses, objection by families accounted for about 60% during this study. Conclusions. This study showed that the maximal number of potential organ donors is about three times higher than the number of effective organ donors. The main reason accounting for ∼60% of the potential donor losses was the high family refusal rate. The year 2007 showed that a higher percentage of deceased organ donors can be procured from the pool of potential donors. All improvements should focus on decreasing the unacceptably high family refusal rates.