Little is known about racial/ethnic differences in preferred methods of disclosing deceased organ donation intentions among persons not previously designating their organ donation preferences publicly or the association of medical mistrust with preferences. We surveyed 307 United States (US) adults who had not yet designated their donation intentions via drivers' licenses or organ donor cards (nondesignators) to identify their preferred disclosure methods (personal discussions with family, physicians, or religious representatives or public registration via mail/telephone/computer, workplace, place of religious worship, or grocery store/bank/post office) and to assess the association of mistrust with preferences. In multivariable models, we assessed racial/ethnic differences in preferences and the influence of medical mistrust on preferences. Nondesignators most preferred discussions with physicians (65%) or family members (63%). After adjustment, African Americans (AAs) were more likely than Whites to prefer discussion with religious representatives. In contrast, AAs and Hispanics were less likely than Whites to prefer registration at a workplace or through mail/telephone/computer. Medical mistrust was common and associated with less willingness to disclose via several methods. Encouraging donation intention disclosure via discussions with physicians, family, and religious representatives and addressing medical mistrust could enhance strategies to improve nondesignators' donation rates.