This study assesses the relationship between public perceptions of the swine flu outbreak and behavior change in England, Scotland, and Wales. A cross-sectional telephone survey was conducted among 997 adults who had heard of swine flu. The main outcomes measured were recommended behavior changes (e.g., increased handwashing, surface cleaning) and avoidance behaviors (e.g., avoiding large crowds, public transport). Results showed that 37.8% of participants reported performing recommended behavior changes, and 4.9% engaged in avoidance behaviors. Perceptions of the severity of swine flu, the risk of infection, the duration of the outbreak, trust in authorities, and the availability of good information were associated with recommended behavior changes. Ethnicity was a significant predictor, with participants from ethnic minority groups being more likely to make recommended changes and engage in avoidance behaviors. The study concludes that effective communication about specific actions to reduce swine flu risks and government plans is crucial, and addressing perceptions of over-hyped outbreaks may be challenging but worthwhile. Further research is needed to understand differing reactions among ethnic groups.This study assesses the relationship between public perceptions of the swine flu outbreak and behavior change in England, Scotland, and Wales. A cross-sectional telephone survey was conducted among 997 adults who had heard of swine flu. The main outcomes measured were recommended behavior changes (e.g., increased handwashing, surface cleaning) and avoidance behaviors (e.g., avoiding large crowds, public transport). Results showed that 37.8% of participants reported performing recommended behavior changes, and 4.9% engaged in avoidance behaviors. Perceptions of the severity of swine flu, the risk of infection, the duration of the outbreak, trust in authorities, and the availability of good information were associated with recommended behavior changes. Ethnicity was a significant predictor, with participants from ethnic minority groups being more likely to make recommended changes and engage in avoidance behaviors. The study concludes that effective communication about specific actions to reduce swine flu risks and government plans is crucial, and addressing perceptions of over-hyped outbreaks may be challenging but worthwhile. Further research is needed to understand differing reactions among ethnic groups.