This study aimed to analyze ageism in formal health care and health professionals' beliefs about infantilization of elderly people, based on the Planned Action Theory (TAP). The dissertation is composed of two chapters. The first chapter supports the discussion of ageism in formal health care. It consists of a systematic literature review carried out in six databases, with the descriptors ageism AND elderly AND health care” and “ageism AND aged AND healthcare”. After the selection of articles (N:64), the introductions and conclusions were cut, as well as their organization in two textual corpuses, submitted to analysis by the Iramuteq software. The results elucidated by corpus 1 demonstrate the presence of ageism in formal health care and its harm to the health of the elderly population, pointing to nursing as the most investigated group and attitudes as the focus of the research objectives. The findings from the analysis of corpus 2 brought to the discussion the importance of new studies on ageism in formal health care and the influence of education as a likely way to prevent and combat its occurrence. Added to this, ageism was identified as a possible barrier in health care for the elderly, and infantilization, socially accepted, was identified as one of its most common expressions. The second study aimed to analyze the beliefs of health professionals about the infantilization of the elderly, based on the Planned Action Theory (TAP). For this, a qualitative research was carried out, with 27 health professionals interviewed, with a non-probabilistic sampling. Data were organized with the help of Iramuteq, and submitted to lexical analyzes of similarity and descending hierarchical classification. The main conclusions identified that behavioral beliefs were linked to attitudes such as playing, changes in speech and use of children's resources; normative beliefs, on the other hand, brought family and caregivers as groups that supported this type of behavior. Control beliefs reveal a health-disease view, in which healthy and active elderly people are not infantilized, but those with advanced age, or those with cognitive and functional alterations, are vulnerable to this form of treatment.