This study aimed to understand how patients perceive their oral health and the resulting oral manifestations of antineoplastic chemotherapy, as well as to analyze the impact of these alterations on oral health-related quality of life. A total of 80 patients undergoing treatment participated in this study. A questionnaire was applied using the Oral Health Impact Profile (OHIP-14) index and open interviews. Items with the highest impact prevalence included "worsened taste of food sensation" (35.00%), "discomfort in eating food" (20.00%), and "feeling stressed" (17.50%). The outpatients showed the highest prevalence scores, whereas the inpatients presented higher quality of life impact severity. The ways in which the patients perceived how their oral alteration affected their quality of life were distinct and subjective. It is important that dentists act together with a multiprofessional team developing strategies to alleviate the impact of the disease and chemotherapy on oral cavity and patients' quality of life.