Influenza is a major cause of morbidity and mortality in Canada. The Laboratory Centre for Disease Control in Ottawa estimates that influenza causes 75,000 hospitalizations and 6,000 deaths on an annual basis. Epidemiological studies consistently find relationships between the presence of influenza virus and increased mortality rates, rates of hospital admission and health services utilization. Increased pneumonia admission rates are consistently associated with influenza. Outcomes plausibly related to influenza infection such as congestive heart failure and chronic lung disease have received less analysis. The objectives of this study are to employ administrative data to examine the age- and sex-specific rates of hospital admission for pneumonia, congestive heart failure and chronic respiratory disease in the elderly population of Ontario for five influenza seasons from 1988-1993. This study is retrospective, descriptive and ecological in nature. No such studies using Canadian data have been published on this topic.