Objectives: To understand the reasons given by family members for not authorizing the donation of organs and tissues. Methods: This is a documentary study. The records of interviews with the families of potential donors, conducted in 2022 by the Organ and Tissue Procurement Organization in the state of Rio Grande do Sul, were analyzed. The study included records related to refusals for donation. Incomplete records or those lacking the family's justification were excluded. Data were collected in March and April 2024 and analyzed using simple descriptive statistics. The research project was approved by the Research Ethics Committee. Results: During 2022, the OPO conducted 121 interviews with family members of potential organ donors; of this total, there were 33 authorizations, 65 refusals, and 23 cases of medical contraindications for donation. Regarding family refusals, of the 65 records analyzed, 39 were excluded due to incomplete information or because they did not contain the justification for refusal. The final sample consisted of 26 interview records. The most common arguments for refusing donation were the patient was not a donor in life, the family was unaware of the deceased’s wishes regarding donation, and the family expressed opposition to donation. Conclusion: The observed justifications included the deceased having declared themselves not to be a donor in life, lack of family consensus on donation, the family’s desire to preserve the integrity of the body, the wait time for the return of the body, religious reasons, unawareness of the deceased’s wishes regarding donation, and family opposition to donation. The results may be used by professionals in various healthcare services to develop strategies to mitigate family refusals.