Quality of life is a multidimensional concept that implies the perception of well-being of a person, considering positive and negative elements, that contemplates the entirety of their existence at a certain period. Health-related quality of life (HRQoL) considers the impact of disease on the quality of life of a patient; it is considered a fundamental outcome in clinical trials and epidemiological studies, particularly in Oncology. Over the past 40 years, a strong and growing line of research has been developed that allows us to measure HRQoL in a valid, reliable, sensitive, precise, reproducible, stable, and comparable way. Worldwide, many instruments have been developed to give us accurate assessments of HRQoL in diverse settings. A basic aspect is that HRQoL represents the point of view of the patient, considering not the opinion and concepts of the health-care worker, but the patient's perception of their own suffering. In this chapter, the available instruments used to measure HRQoL in patients with cancer in Mexico are briefly described, along with their advantages or weaknesses.