In an attempt to gain insight into the motivations of blood donors and nondonors, 2 paper and pencil questionnaires were developed and mailed to approximately 7000 individuals. In response, 1429 nondonors and 200 donors completed and returned usable questionnaires. Among donors, awareness of the need for blood, altruism and investment for the future (blood credit) were the chief motivating factors. Among nondonors the major deterrent was belief in medical disqualification. Of the 33% who claimed medical disqualification, 40% gave clearly invalid or questionable reasons. Fear was a substantial factor among nondonors, but not as great a deterrent to blood donation as previously thought. A dimension focusing upon failure to confront the issue of donating was derived and found to equal or exceed fear in importance. The influence of such items as sex, age, number of donations and number of children on reasons expressed was examined. The major results were compared with the findings on previous studies. An approach-avoidance model of blood donation was outlined, and implications for donor recruitment were discussed.