Blood donors' preferences for blood donation for biomedical research.

Familiarity and reciprocity were key to the relationship between the blood service and blood donors. Donation for research introduces a new, more complex context to blood donation. Challenge to recognize concrete outcomes and benefits of donation may affect willingness to donate for research. Transparent communication of the role of the blood service in research and of the beneficiaries of the research is essential in maintaining trust. These results will help blood services in their planning to recruit blood donors for research projects.