Abstract Background: This paper describes the personal and societal impact of a small outbreak of influenza in the United Kingdom over the winter 1999/2000. Methods: All adults hospitalised with acute respiratory symptoms were recruited into a case control study to examine the effectiveness of the influenza vaccination. All patients were admitted to a large district general hospital, serving a population of 190,000. Details were recorded of age, chronic disease, smoking behaviour, alcohol consumption, influenza and pneumococcal vaccination status. While in hospital, utilisation of hospital facilities, length of stay, use of critical care facilities and fatality were recorded. Clinical specimens were taken for serology and chest X-ray findings recorded. These individuals and community controls were followed up for an addition 2 years to compare their pre- and post-influenza morbidity and health-seeking behaviour. Results: Case recruitment occurred from week 51/99 to week 5/00 when influenza was circulating in the community. A total of 186 women and 160 men were recruited with an average age of 68.6 years. Eighty-nine percent had pre-existing chronic disease, stayed on average at least 10 days, the length of stay increasing dramatically with extreme age; 11% of the cases received intensive or critical care during the admission and, overall, the case fatality rate was 15%, 23% in the over-65 age group while hospitalised. Only 33% of the patients with pre-existing chronic disease received the influenza vaccination and only 21% pneumococcal. Follow-up of cases over a further 2 years showed that 94 (28%) had died compared to 25 (3.8%) of the matched controls. They suffered an increased number of hospital admissions, poorer heath and increased morbidity and mortality. Conclusions: Even small outbreaks of influenza have a profound impact on the lives of individuals and society. This study reinforces the need for increased efforts to improve vaccine uptake in those most at risk and the consequences for not taking such action.