OBJECTIVE: To assess the predictive factors of influenza vaccination among Italian adults, focusing on socioeconomic differences. METHODS: A cross-sectional study was carried out using interview and self-reported data on 102,095 subjects aged 25-89 years from the national survey "health conditions and health care services use" conducted in Italy in 1999-2000. Analyses were stratified by age and multiple logistic regression models were used to estimate odds ratios (OR) of influenza vaccination. RESULTS: Approximately one in six individuals (17.3%) received an influenza vaccine in the previous 12 months. Older age, poor health status and former smoking were all positively associated with influenza vaccination (P-value<0.05). Lower educated individuals and subjects with manual occupations were less likely to be vaccinated than those better off, with an OR ranging from 0.65 (95% CI 0.55, 0.77) to 0.82 (95% CI 0.71, 0.93). Among individuals aged 65-89 there was no apparent influence of both variables on the likelihood of receiving the influenza vaccine. CONCLUSIONS: Socioeconomic inequalities in influenza vaccine uptake were present among the adults but not among the elderly. Because in Italy the National Health Service provides influenza vaccination to the elderly free of charge, it is possible that this policy attenuated the socioeconomic differential.