[Katz Index on elderly functionality evaluation].

The growing number of the elders has been increasing the need for the use of functional evaluation instruments. But such use should be done in such a way as to allow comparisons among the various studies and the different realities. Among those instruments, the Index of Activities of Daily Living (ADL), developed by Sidney Katz, is one of the oldest and one of the most frequently mentioned in Brazilian and international literature. Different articles have been showing, however, modified versions of that instrument, thus making it difficult for readers to correctly use it. This paper has the objective of making a historical account of the development, evolution and correct use of Sidney Katz's Index of Independency in the Daily Living, as well as the changes and adaptations it has gone through time, with the author's agreement, so as to contribute for the standardization of the research information related to functional evaluation in gerontology.