Sweden has about 135 heart beating solid organ donors per year among 9.2 million inhabitants. Earlier estimations have suggested that 250-300 of potential heart beating donors might be available in the country annually. The present study is the first nationwide survey to establish the number of potential heart-beating donors, based on all patient deaths in Swedish intensive care units (ICUs). In the present study, a potential heart-beating solid organ donor was strictly defined as "a patient in an ICU on mechanical ventilation with the diagnosis of brain death." All 85 eligible ICUs reported all patient deaths over a 3 month period of October through December 2007. The instrument consisted of 10 questions. The majority of data were entered electronically by the ICU staff into the "Swedish Intensive Care Registry." The total number of reported patient deaths was 875 with 7.4% of patients who died meeting the criteria for a potential heart-beating solid organ donor. Actually 51% of them became donors. Reasons for not becoming a donor were refusals in 31%, medical reasons in 14%, impossibility to obtain consent in 1.5%, and no suitable recipient in 3%. Furthermore, 1.5% of patients did not become donors because of preferential forensic examinations. The main conclusion of the study was that the actual number of potential heart-beating solid organ donors in Sweden seems to be less than earlier estimates. Another interesting observation is the existence of a group of artificially ventilated, brain injury patients in whom the death was diagnosed by cardiac arrest. We think that this group of patient deaths deserves further investigation in future projects.