This paper considers the bioethics of estranged biological kin, who are biologically related people not in contact with one another (due to adoption, abandonment, or other long-term estrangement). Specifically, I am interested in what is owed to estranged biological kin in the event of medical need. A survey of current bioethics demonstrates that most analyses are not prepared to reckon with the complications of having or being estranged biological kin. For example, adoptees might wonder if a lack of contact with (...) biological kin could someday affect their medical care (or affect the medical care of their biological relatives). Estranged biological kin, such as adoptees, present us with a chance to think about human connection. After sketching several organ-donation and adoption tropes, I argue that a feminist analysis of vulnerability and dependency is helpful for understanding the confusing ties of estranged biological kin. I conclude by proposing a medical registry that would put adoptees and others in touch with their estranged biological kin on a medically as-needed basis. (shrink)