OBJECTIVES: In this study, population-based analysis is used to study the extent to which characteristics such as age, sex, socioeconomic status, and region of residence are associated with different patterns of pharmaceutical use. It also includes an examination of whether pharmaceutical use is responsive to differential health needs across the population. RESEARCH DESIGN: Indicators of access, intensity of use, and total expenditures are used to describe Manitobans' use of pharmaceutical agents, consistent with the POPULIS framework. MEASURES: Several rate-based measures have been developed for this purpose: the number of residents who are pharmaceutical users; the number of prescriptions dispensed; the number of different drugs dispensed; the total number of defined daily doses (DDDs) dispensed; and expenditures for pharmaceuticals. The DDD measurement provides a cumulative assessment of total drug use (i.e., across multiple drug categories) and is a useful indicator of a population's total drug exposure. RESULTS: Patterns of use of pharmaceuticals follow patterns similar to those patterns in earlier POPULIS studies on health care access, intensity, and expenditures. In areas where health is generally poorer, a greater number of prescriptions are dispensed. The highest use of pharmaceuticals also was found in the lower-income quintiles and among those at greatest socioeconomic risk, traditionally those with the poorest health status. CONCLUSIONS: This kind of population-based pharmaceutical information can help monitor the effectiveness of policy initiatives, as well as serve to better manage pharmaceutical use within the health care system.