The effect of treatment on the health status of patients suffering from claudication of the lower limbs has seldom been studied, and their quality of life (QQL) not at all. These terms are distinguished and defined. Studies of both are important, but it is believed that QOL is of more interest to the patient, as representing the individual's appreciation of and reaction to factors of personal importance. The many methods employed can be classified according to (a) their emphasis on the individual as against the group and (b) their attention to internal as against external variables. Problems met in creating new methods for the study of QOL are discussed. These include eliciting features of their condition that are of specific importance to patients, and establishing the different degrees of importance that individuals attach to these. The new instrument must be phrased in an acceptable, reliable, and valid form for subsequent use. Its validity is most convincingly demonstrated by the ability to discriminate between patients with different degrees of disease severity or those who have been differently treated, as in a clinical trial. Comparative advantages of general and specific methods of inquiry, results expressed as profiles or single indicators, and the influence of contextual factors (bias due to timing, the effect of the investigator-subject relationship, etc.) are also discussed.