In France, annual influenza vaccination is recommended and free of charge for children with chronic disease (chronic lung, heart or kidney disease, diabetes, haemoglobinopathy, immune deficiency). The national goal is to reach 75% influenza vaccination coverage by 2008, but data on coverage in high risk children are limited. OBJECTIVES: To estimate the influenza vaccination coverage in children with an underlying chronic health condition in the Paris region, during in- or out-patient visit at hospital. METHODS: A multicentre cross-sectional descriptive study was carried out over 2 months before the 2004-2005 flu vaccination campaign in 7 French paediatric hospitals (Paris region). Inclusion criteria for this survey were: children aged 6 months to 18 years, with an underlying chronic disease requiring annual influenza vaccination, with a vaccination card available, so as to check their vaccination status. Reasons for non vaccination were recorded. RESULTS: Data from 239 children were analysed. 56% of patients were males (mean age: 8.1 years). Two patients had 2 separate underlying chronic disorders; 69% had a haemoglobinopathy, 16.3% had a chronic respiratory disease, and 7.5% had diabetes. The influenza vaccination rate for 2003-2004 was 43.7% (haemoglobinopathy: 55.5%; chronic respiratory diseases: 12.8%). This rate increased from 20.4% to 43.7% between 1999 and 2003. Less than 16% of parents remembered having received a voucher for free vaccination from the National Health Insurance Agency. CONCLUSION: Efforts are still needed to achieve the 2008 objectives of 75% coverage.