The purpose of this article is to review the instruments developed to measure functional status in patients with chronic obstructive pulmonary disease. Because the ability to carry out day-to-day activities is of primary importance to patients with chronic obstructive pulmonary disease, it is necessary for clinicians to understand which instruments provide the best measures of patient activity levels. Furthermore, as a critical outcome in managed care services, pulmonary critical pathways, and patient disability, the measurement of functional status in clinical practice assumes greater relevance. Functional status instruments in this review will refer to questionnaires measuring the day-to-day activities of patients. Questionnaires reviewed will include those that provide measures of general health status with activity-specific items, as well as questionnaires specifically designed to evaluate patients with pulmonary disease. The psychometric strengths, reliability and validity, and clinical utility of the instruments will be presented.