Age-related effects on health service utilization are not well understood. Most previous studies have examined only a single specific health care service or disease condition or have focused exclusively on economic variables. We aim to measure age-related change in health care utilization among the elderly. A population-based retrospective cohort study was conducted using linked data from four administrative databases (OHIP, ODB, CIHI and RPDB). All Ontario residents over the age of 65 years and eligible for public health coverage were included in the analysis (approximately 1.6 million residents). Main outcome measures include utilization indicators for family physician visits, specialist physician visits, Emergency Department visits, drugs, lab claims, X-rays, inpatient admissions, CT scans and MRI scans. The mean number of utilization events for Ontarians aged 65+ years for the 1-year study period was 70 events (women = 76, men = 63). The overall absolute difference between the 65-69 age group and the 85+ age group was 155% (women = 162%, men = 130%), or 76 more events per person in the older group (women = 82, men = 61). Women averaged more events per person than men, as well as greater percentage differences by age. Drugs and diagnostics account for the majority of events. Only MRI and specialist visits were not higher among the older age groups. At the population level, overall health care utilization would appear to increase significantly with age. It is unclear whether increasing health care utilization prevents morbidity, decreases mortality, or improves quality of life.