This investigation set out to study the epidemiology and distribution of non- capsulate H. influenzae in Morecambe Bay. All H. influenzae isolates from patients in hospital and the community were collected over a 2 year period. These were tested using traditional culture, biochemical and molecular techniques. Data collected included medical history, smoking history, demographic and socio-economic details for 762 patients. The distribution of housing types in Morecambe Bay was different from the rest of the UK. Housing types for patients in the study were not representative of the local population profile. Most infections were found in patients living in urban areas. Less affluent patients were most likely to have a history of smoking, especially patients aged over 50 years. Patients presenting with more than 1 episode of infection during the study were more likely to have smoked. Some patients who presented with more than 2 episodes of infection were co-Ionised by non-capsulate H. influenzae with the same sequence type (ST) for up to 2 years, some acquired different STs and some STs evolved into closely related STs. There was no significant change in the rate of antibiotic resistance across Morecambe Bay between 2001 and 2005, although severity of chest disease did have a significant effect on ampicillin resistance. Age did not have a significant impact on ampicillin resistance but more elderly patients were infected by multiple antibiotic resistant bacteria. The ICEHin1056 element did offer an !I explanation for ampicillin resistance involving the bla gene. ICE negative strains may have acquired resistance from other bacteria colonising the airway. Different age populations were found in the 3 hospital areas. There was no significant difference in numbers of male and female patients presenting with eye or chest infections but significantly more ear infections were found in males. The findings of this study suggest that most non-capsulate H. influenzae chest infections were found in the less affluent elderly population.