 Eight hundred employees of an urban tertiary care hospital, 200 each from the following four categories: professional staff, resident physicians, registered nurses, and licensed practical nurses comprised the study group. Subjects were randomly assigned to receive: 1 no intervention, 2 a reminder letter for flu vaccine, 3 a raffle ticket to win a free Caribbean vacation with flu vaccine administration, or 4 both the reminder letter and raffle ticket. We compared the proportion of employees receiving vaccination and participating in the raffle across groups. 