The evaluation of quality of life in chronic liver disease is a crucial outcome measure of all interventions on patients. This paper presents a variety of clinical situations in which it is essential to assess quality of life: in fact, chronic liver disease ranges from asymptomatic B or C hepatitis to liver failure and transplantation. It also points out some methodological pitfalls: in particular, the choice of validated questionnaires, the use of generic instruments versus specific ones, timing of administration, choice of cross-sectional versus longitudinal studies, control of bias (selection and attrition) and other relevant methodological issues.