This study was carried out from April to December 1990 in the commune of Valdivia, Chile and involved 207 physicians, nurses, midwives, and nurse-midwives. The objective was to determine the relationship between subjective attitude and personal behavior on the part of these health professionals with regard to the practice of monthly breast self-examination (BSE). The data were collected by means of an instrument designed to measure attitudes, which was prepared by Victoria Lee Champion (1984) on the basis of the health beliefs model of Becker, et al. (1974). Also included were questions aimed at ascertaining the personal and sociodemographic background of the professionals surveyed and their knowledge of several aspects of breast cancer and BSE. The information collected was subjected to the following tests of validity and reliability: Person product-moment correlation coefficient r, split half method, Spearman-Brown R coefficient, Cronbach alpha coefficient, and the Chi-square test to determine the degree of association between the variables. The results showed that although 79% of the women studied had ample knowledge of many aspects of breast cancer and 82% were aware of the benefits of BSE, only 28% practiced it on a monthly basis. It is alarming that health professionals, who are responsible for teaching prevention measures to other people, have yet to assume responsibility for protecting their own health insofar as early detection of breast cancer is concerned.