Objectives: This study examined the relative importance of factors relating to vaccine characteristics, social normative influence and convenience in access to vaccine for determining decision making for seasonal influenza vaccination (SIV) among healthcare personnel (HCP), aiming to optimize existing influenza vaccination programmes for HCP. Methods: A discrete choice experiment (DCE) was conducted in HCP working in public hospitals in Hong Kong. The DCE was designed to examine the relative importance of vaccine characteristics (vaccine efficacy and safety), social normative influence reflected by the proportion of HCP colleagues intending to take SIV, and convenience in access to vaccine indicated by vaccination programme duration, vaccination location, vaccination arrangement procedure and service hours in determining influenza vaccination choice among HCP. Mixed logit regression modelling was conducted to examine the preference weight (b) of factors included in the DCE for determining vaccination choice. Results: Vaccination probability increased with increase in vaccine efficacy (b = 0.02 for per 1% increase), vaccination location changing from ''designated staff clinic" to ''mobile station" (b = 0.37), vaccination arrangement procedure changing from ''by appointment" to ''by walk-in" (b = 0.99), but decreased with the increase in probability of mild reactions to vaccination (b = À0.05 for per 1% increase). Conclusion: Vaccine safety was judged to be more important than vaccine efficacy for determining vaccination choice. Arranging vaccination service by walk-in and implementing mobile vaccination station should be considered in future SIV programmes to compensate for the effect of perceived low vaccination efficacy and concerns about vaccine safety to promote SIV uptake among HCP.