In Public Health exists a growing tendency to evaluate the impact of health problems both on the quality of life of the persons involved as well as the use of health services. In this sense, the evaluation of incapacity is acquiring ever greater relevance. The Barthel Index is an instrument widely used to this end and measures the capacity of the person for the execution of ten basic activities in daily life, obtaining a quantitative estimation of the subject's level of dependency. The Barthel Index has been used, since its introduction in 1955, resulting in numerous versions, as well as serving as a standard of comparison with other scales. It is an easily applicable method, with a high level of reliability and validity, capable of detecting changes, easy to interpret and the application of which is not problematic. On the other hand, its adaptation to different cultural environments is almost immediate. Although it has a few limitations, the Barthel Index may be recommended as a selection method for measuring physical incapacity, both in clinical practice as well as in epidemiological investigation and Public Health.