The objective of this study was to understand the perception of health professionals of two definitions of frailty in elderly people. The sample consisted of twelve health professionals, who work in a Geriatrics Ambulatory. The tools used for data collection were individual semi-structured interviews, and the questionnaire Definitions of Frailty, developed for that purpose. Data were organized and analyzed using the Collective Subject Discourse method, which consists of key-expressions, central-ideas and collective subject discourse. The results indicated that the health professionals have got difficulties to accept a one-dimensional definition of frailty, which is in accordance with the international literature. The six Central Ideas (CI) that emerged from the discourses were: 1) the definitions are complementary; 2) there is no potential for prevention; 3) defining frailty is a complex task; 4) what is the concept of frailty? 5) the multidimensional definition is complete; 6) frailty is a state that can last for life. The participants believe that these definitions complement each other, since frailty encompasses an interaction of biological, psychological, and social factors throughout the lifespan. Only one professional accepted the multidimensional definition as complete. Defining frailty is a rather complex task.13411811188