Objective: to assess motivating factors of healthy elderly people to comply with influenza vaccination. Design:survey of healthy elderly people invited by mail by their general practitioner to come for influenza vaccination. Compliance and the personal characteristics of gender, age and medical insurance were recorded by the general practitioner. A postal questionnaire assessing socio-psychological factors was sent to all non-compliant patients and to a random sample of 30% of the compliant patients. Setting: seven family practices with a total of 26000 patients in The Netherlands. Patients: 505 healthy elderly people over 65. Main outcome measures: odds ratios (ORs) for non-compliance by personal characteristics and socio-psychological factors, adjusted by multiple logistic regression analysis; decisive reason whether to comply. Results: non-compliance was 16%. Correlations between personal characteristics and non-compliance were low except for age: those under 75 were less compliant than those over 75. Elderly people endorsing the statement about the vaccine's serious side-effects displayed the highest non-compliance [adjusted OR 216; 95% confidence interval (CI) 16.2 to 2883]; patients judging their own health to be good were also less compliant (adjusted OR 57.9; 95% CI 4 A to 770). The belief of not being susceptible to influenza was the most frequently mentioned reason for not complying, while the general practitioner's mail cue was the most common reason for complying. Conclusions: in healthy elderly people, fear of the side-effects of influenza vaccination and perceived good health seem to be the main factors leading to non-compliance. Better and more specific information about the paucity of systemic side-effects should accompany the invitations.