Evaluation of the effectiveness of treatment for chronic obstructive pulmonary disease (COPD) requires the assessment of both clinical and physiological measures. Parameters such as the forced expiratory volume in 1 s are well established in providing an indication of the degree of airflow limitation. However, additional measurements, such as dyspnoea, functional status and health status, are required to provide a complete picture of COPD. Indeed, dyspnoea is the predominant symptom of COPD experienced by the patient, which treatment is designed to reduce. Methods of assessing dyspnoea have developed over the previous five decades. The most widely used instruments for assessing the impact of dyspnoea are the baseline dyspnoea index, the transition dyspnoea index and the Medical Research Council Questionnaire. A more comprehensive approach to the assessment of disability caused by dyspnoea and fatigue is provided by assessments of functional status, such as the pulmonary functional status and dyspnoea questionnaire. Respiratory-specific health status questionnaires, such as the St. George's Respiratory Questionnaire, attempt to capture the wide range of effects of COPD into a single score that reflects the overall impact of the disease. Developing the means to measure the effects of COPD is important, both in terms of understanding disease pathophysiology for research purposes, and in terms of accurately assessing the effects of treatment on the patient. Future developments will include computerising these methodologies to permit faster and more individual patient-centred measurements.