Knowledge, attitude and behaviour regarding influenza immunization were evaluated in 519 health care workers (HCWs) from high risk hospital areas because of this target group's historically poor acceptance rates. The results of this self-administered questionnaire survey indicated that HCWs' knowledge regarding influenza and influenza vaccine was generally satisfactory. However, only approximately one half of the HCWs knew who should receive influenza vaccine and why it is important. HCWs with good knowledge of influenza and the influenza vaccine were more likely to recommend vaccine to their patients and to their co-workers/family, but were not more likely to receive it themselves. Experiencing post-vaccine symptoms for more than one day significantly reduced the willingness of HCWs to accept and to recommend vaccine. HCWs who heard about influenza vaccine from their doctors indicated significantly more willingness to receive vaccine and to recommend vaccine to co-workers and family. Questionnaire survey of willingness to accept influenza vaccine overestimated actual acceptance, as only 35.7% of the HCWs who had positive views regarding the influenza vaccine actually received the vaccine during the following influenza season. While knowledge about the vaccine, previous experience with perceived adverse symptoms and promotion by family doctor significantly influenced questionnaire responses, hearing about the vaccine from the occupational health department, being on a geriatric ward or being a unit assistant were the most significant factors in actually being vaccinated. Thus, occupational health departments must continue their efforts to promote the influenza vaccine actively and to make it as accessible as possible.